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End User License Agreement (EULA)

Mastery — Adaptive Vocabulary Mastery System
Effective Date: February 23, 2026

1. Agreement

This End User License Agreement ("EULA") is a legal agreement between you ("you," "your") and Valentin Seehausen, operating as a sole proprietor under the laws of Germany ("Licensor," "we," "us," "our"), for the use of the Mastery mobile application, including any updates, upgrades, and related documentation (the "Application").

By downloading, installing, or using the Application, you agree to be bound by this EULA. If you do not agree, do not download, install, or use the Application.

This EULA supplements the Apple Media Services Terms and Conditions or Google Play Terms of Service, as applicable.

2. License Grant

Subject to your compliance with this EULA, we grant you a limited, non-exclusive, non-transferable, revocable license to download, install, and use the Application on devices that you own or control, solely for your personal, non-commercial use.

3. License Restrictions

You may not:

  • Copy, modify, or distribute the Application or any portion thereof
  • Reverse-engineer, decompile, disassemble, or attempt to derive the source code of the Application, except to the extent expressly permitted by applicable law (including EU Directive 2009/24/EC on the legal protection of computer programs)
  • Rent, lease, lend, sell, sublicense, or otherwise transfer the Application or access thereto to any third party
  • Remove, alter, or obscure any copyright, trademark, or other proprietary notices in the Application
  • Use the Application for any unlawful purpose or in any manner that violates this EULA

4. Intellectual Property

The Application, including its design, code, algorithms (Memory Mirror, FSRS-based scheduling, adaptive card selection), enrichment content, user interface, graphics, and branding, is owned by the Licensor and protected by copyright, trademark, and other intellectual property laws of Germany, the European Union, and international treaties.

This EULA does not transfer any ownership rights to you. All rights not expressly granted herein are reserved by the Licensor.

5. User Data

Your use of the Application involves the collection and processing of personal data as described in our Privacy Policy. By using the Application, you acknowledge that you have read and understood the Privacy Policy.

You retain ownership of your learning data (words, review history, vocabulary progress). We process this data solely to provide and improve the Service.

6. Subscriptions and In-App Purchases

The Application may offer subscriptions and in-app purchases. Purchases made through the Apple App Store are processed by Apple; purchases made through the Google Play Store are processed by Google. You agree to the payment terms of the applicable platform.

Subscription terms, including pricing, renewal, and cancellation, are described in our Terms of Service.

7. Third-Party Services

The Application integrates with third-party services (Kindle, Chrome, Supabase, Stripe, RevenueCat). Your use of these services is subject to their respective terms. We are not responsible for the availability, accuracy, or practices of third-party services.

8. Disclaimer of Warranties

TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, THE APPLICATION IS PROVIDED "AS IS" AND "AS AVAILABLE" WITHOUT WARRANTIES OF ANY KIND. WE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT.

We do not warrant that the Application will be error-free, uninterrupted, or free of harmful components. We do not guarantee specific learning outcomes or vocabulary acquisition results.

Nothing in this EULA excludes warranties that cannot be excluded under applicable mandatory law, including EU consumer protection law.

9. Limitation of Liability

TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW, THE LICENSOR SHALL NOT BE LIABLE FOR ANY INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL, OR PUNITIVE DAMAGES ARISING FROM YOUR USE OF OR INABILITY TO USE THE APPLICATION.

OUR TOTAL LIABILITY SHALL NOT EXCEED THE AMOUNT YOU PAID FOR THE APPLICATION OR SUBSCRIPTION IN THE 12 MONTHS PRECEDING THE CLAIM, OR €100, WHICHEVER IS GREATER.

Nothing in this EULA limits liability for death or personal injury caused by negligence, fraud, or any liability that cannot be excluded or limited under applicable law.

10. Termination

This EULA is effective until terminated. Your rights under this EULA will terminate automatically if you fail to comply with any of its terms.

Upon termination, you must cease all use of the Application and delete all copies from your devices. We may also terminate your license at any time for any reason by providing notice.

Termination does not affect any rights or obligations that accrued prior to termination, including any right to a refund under applicable consumer law.

11. Apple-Specific Terms

If you downloaded the Application from the Apple App Store, the following additional terms apply:

  • This EULA is between you and the Licensor, not Apple. Apple is not responsible for the Application or its content.
  • The license granted is limited to use on Apple-branded products that you own or control, as permitted by the App Store Terms of Service.
  • The Licensor, not Apple, is responsible for maintenance and support of the Application.
  • In the event of any failure of the Application to conform to any applicable warranty, you may notify Apple and Apple will refund the purchase price (if any). Apple has no other warranty obligation with respect to the Application.
  • The Licensor, not Apple, is responsible for addressing any claims relating to the Application, including product liability claims, claims that the Application fails to conform to legal or regulatory requirements, and consumer protection claims.
  • In the event of any third-party claim that the Application infringes a third party's intellectual property rights, the Licensor, not Apple, is solely responsible for the investigation, defense, settlement, and discharge of such claim.
  • Apple and its subsidiaries are third-party beneficiaries of this EULA and, upon your acceptance, have the right to enforce it against you.

12. Google Play-Specific Terms

If you downloaded the Application from the Google Play Store, this EULA is between you and the Licensor, not Google. Google is not responsible for the Application. Google has no obligation to provide maintenance, support, or warranty for the Application.

13. Export Compliance

You represent and warrant that you are not located in a country that is subject to a U.S. or EU government embargo, and that you are not listed on any U.S. or EU government list of prohibited or restricted parties.

14. Governing Law

This EULA is governed by the laws of the Federal Republic of Germany. If you are a consumer in the EU, you also benefit from mandatory consumer protection provisions of the law of your country of residence.

15. Severability

If any provision of this EULA is held to be invalid or unenforceable, the remaining provisions shall remain in full force and effect.

16. Changes to This EULA

We may update this EULA from time to time. We will notify you of material changes through the app or by email at least 30 days before they take effect. Continued use of the Application after the effective date constitutes acceptance of the updated EULA.

17. Contact Us

If you have questions about this EULA, contact us at:

Valentin Seehausen
Email: privacy@mastery-app.com