End User License Agreement

Last updated: August 15, 2026

This End User License Agreement (the "EULA") is a binding agreement between you and Castle 11 Labs, LLC, a Delaware limited liability company ("Castle 11 Labs," "we," "us," or "our"), with a notice address at 169 Madison Ave, STE 58067, New York, NY 10016.

This EULA governs your use of Castle 11 Labs audio plugin software, including Thirty-Six, together with its documentation, presets, and any updates we provide (the "Software"). By installing, activating, or using the Software, you accept this EULA. If you do not accept it, do not install the Software; if you purchased it, see our Refund Policy.

Beta versions of our software are not covered by this EULA; they are governed by the separate Castle 11 Labs Beta Software Agreement.

1. License Grant

1.1 Purchased licenses. Subject to your payment of the purchase price and your compliance with this EULA, we grant you a perpetual, worldwide, non-exclusive, non-transferable license to install and use the Software, in object code form, for your personal or internal business music-production purposes.

"Perpetual" means the license does not expire. It does not mean we promise the Software will remain compatible with future operating systems, plugin hosts, or hardware forever - see Section 5.

1.2 Trial licenses. If we issue you a free trial, we grant you a time-limited, worldwide, non-exclusive, non-transferable license to install and use the Software on the same terms, for 14 days from the day the trial starts and on one machine rather than two. A trial license expires on its own at the end of that period and cannot be renewed or extended. One trial per product per person. Every other term of this EULA applies to a trial license while it runs, except that the activation limit in Section 2.1 is replaced by the one-machine limit in this Section. A trial does not convert into a purchased license: buying the Software issues you a separate, new license under Section 1.1.

2. Activations

2.1 Limit. You may activate and use the Software on up to 2 machines at the same time (one machine for a trial license, see Section 1.2). All activated machines must be owned or controlled by you and used only by you (or, for a business licensee, by one user at a time per license).

2.2 Moving machines. Depending on how a machine was activated, we may grant you a revocable privilege to deactivate that machine and free its activation for use on another machine. This privilege is available for machines activated online through our license activation system; it is not available for machines activated permanently offline. If a machine is lost, stolen, or dead and you cannot deactivate it yourself, contact support@castle11labs.com and we will reset the activation within reason.

2.2a Activation service availability. If our license activation service becomes unavailable for an extended period or is discontinued, we will make reasonable efforts to provide an alternative activation method or to unlock affected licenses so they continue to function offline. This EULA does not guarantee a specific outage response time or unlock mechanism.

2.3 How activation works. To activate, the Software opens a browser window where you sign in to the Portal; it then validates your license against our licensing service. There is no license key to type. A machine identifier (such as a hostname or device fingerprint) may be processed to count activations, as described in our Privacy Policy.

2.4 License keys. We do not provide you with your full license key: the Portal shows only a partial key sufficient to identify your license, and your key is stored in obfuscated form wherever it resides on your machine. Attempting to extract, decode, or otherwise reveal your license key in full is treated as reverse engineering under Section 3.

3. Restrictions

You may not, and may not permit anyone else to:

  • sell, resell, transfer, assign, rent, lease, lend, sublicense, or share the Software or your license, in whole or in part, to or with any other person or entity - licenses are personal to the original purchaser and are non-transferable;
  • copy the Software except as reasonably necessary for installation on your activated machines and for backup;
  • reverse engineer, decompile, disassemble, or otherwise attempt to derive the source code, algorithms, or underlying DSP of the Software, except to the limited extent that applicable law (for example, Article 6 of EU Directive 2009/24/EC) grants you a right to do so for interoperability that cannot be excluded by contract, and then only to the extent the necessary interoperability information is not otherwise readily available to you, using any information obtained solely to achieve that interoperability and not to build a substantially similar competing product;
  • modify, adapt, or create derivative works of the Software;
  • remove, alter, or circumvent license validation, activation, copy protection, or proprietary notices, including by extracting, decoding, or deobfuscating your license key;
  • use the Software to develop a competing product, or use it in violation of applicable law; or
  • distribute the Software's presets, impulse responses, or other bundled content on a standalone basis.

4. Ownership

The Software is licensed, not sold. Castle 11 Labs and its licensors retain all right, title, and interest in and to the Software, including all intellectual property rights. No rights are granted to you other than those expressly stated in this EULA.

5. Updates, Compatibility, and Support

5.1 Updates. We may provide updates, bug fixes, and improvements to the Software at our discretion. Updates within the same major version as the version you purchased (for example, all 1.x releases if you purchased a 1.x version), including bug-fix and compatibility updates, are provided at no additional charge. A new major version (for example, moving from 1.x to 2.0) may be offered as a paid upgrade.

5.2 Compatibility. The Software is designed for the operating systems and plugin formats (VST, AU, AAX) stated on the product page at the time of purchase. Operating systems, DAWs, and hardware platforms change over time, and we do not warrant that the Software will remain compatible with future versions of them, although we intend to provide reasonable compatibility updates for supported products.

5.3 Support. We provide email support at support@castle11labs.com on a reasonable-efforts basis. We do not guarantee response times or that every issue can be resolved.

6. Term and Termination

This EULA is effective from your first installation or activation and continues until terminated.

6.1 Termination for breach. We may terminate this EULA if you materially breach it and, where the breach is curable, fail to cure it within 14 days of notice. We may terminate immediately for breaches of Section 2.4 or Section 3 (license sharing, transfer, reverse engineering, or circumvention).

6.2 Refund. If you receive a refund for the Software, this EULA and your license terminate automatically and your license is revoked and all machine activations are deactivated.

6.3 Effect of termination. On termination, your license ends and you must stop using the Software, deactivate it, and delete all copies. Sections 3, 4, 7, 8, and 9 survive termination. Termination does not entitle you to a refund except as provided in the Refund Policy.

7. Warranty Disclaimer

To the fullest extent permitted by law, the Software is provided "as is" and "as available," and we disclaim all warranties, express or implied, including merchantability, fitness for a particular purpose, and non-infringement. We do not warrant that the Software will be error-free or uninterrupted, or that it will meet your requirements.

Consumer rights. If you are a consumer, you may have statutory rights that this Section does not affect - including, for consumers in the EU and UK, statutory remedies if digital content does not conform to the contract, and for consumers in California, rights under the California Consumer Legal Remedies Act and California Unfair Competition Law. Nothing in this EULA excludes, limits, or waives rights that cannot be excluded, limited, or waived under the law of your country or state of residence.

8. Limitation of Liability

To the fullest extent permitted by law:

8.1 Neither party is liable for indirect, incidental, special, consequential, or punitive damages, or for lost profits, revenues, recordings, projects, data, or goodwill, arising out of or relating to this EULA or the Software, even if advised of the possibility of such damages. In particular, we are not liable for the loss of audio projects or sessions - please maintain backups.

8.2 Our total aggregate liability arising out of or relating to this EULA or the Software is limited to the amount you paid for the Software.

8.3 Nothing in this EULA limits or excludes liability for death or personal injury caused by negligence, for fraud or fraudulent misrepresentation, for gross negligence or willful misconduct, or for any other liability that cannot be limited or excluded under applicable law. If you are a consumer in the EU or UK, the limitations in this Section apply only to the extent permitted by the law of your country of residence.

9. Governing Law and Disputes

This EULA is governed by the laws of the State of Delaware, without regard to its conflict-of-laws rules. Disputes arising out of or relating to this EULA or the Software are subject to the dispute resolution terms - including the arbitration agreement, class action waiver, opt-out right, and the carve-outs for consumers outside the United States - in Section 14 and Section 15 of our Terms of Service, which are incorporated into this EULA by reference.

10. Export Compliance

You may not use or export the Software in violation of applicable export control and sanctions laws, and you represent that you are not located in an embargoed country or on a restricted-party list.

11. General

If any provision of this EULA is held unenforceable, it will be enforced to the maximum extent permissible and the remainder will remain in effect. Our failure to enforce a provision is not a waiver. You may not assign this EULA or your license; we may assign this EULA in connection with a merger, acquisition, or sale of assets, provided the assignee assumes our obligations to you. This EULA, together with the Terms of Service, Refund Policy, and Privacy Policy, is the entire agreement between you and us regarding the Software.

12. Contact

Castle 11 Labs, LLC
169 Madison Ave, STE 58067
New York, NY 10016
legal@castle11labs.com

Questions about any of these terms? Email legal@castle11labs.com.