Terms of Use

1. Service

Derso is a learning platform offering AI-powered voice lessons, interactive study sessions, and level exams. By using the service, you accept these terms. If you are under 18, you must use the service with parent or guardian approval.

2. Account

You are responsible for your account security. Account sharing, bulk automated access, and abuse of the service may lead to account suspension.

3. Subscriptions and pricing

The free tier comes with daily usage quotas. Paid subscriptions (e.g. Derso English Premium, monthly or yearly) renew automatically at the end of each period at the price shown at checkout. If a free trial is offered on the yearly plan and you cancel before it ends, you are not charged. You may cancel at any time; cancellation takes effect at the end of the current period, and fees for the current period are not refunded (your mandatory consumer rights remain reserved).

Purchase channels: (a) For purchases made through the App Store, Apple is the merchant of record; billing, renewal, cancellation, and refunds are governed by the Apple Media Services terms and Apple's refund process, and the subscription is managed in your device's subscription settings. (b) For purchases made on the web, Derso is the merchant and payment is processed by Stripe; cancellation and refund terms are described in the Refund and Withdrawal Policy.

Fair use: "unlimited conversations" is subject to fair use so the service stays sustainable for everyone - Premium is designed for up to 5 conversation sessions per day, and a session consists of roughly 20-25 exchanges. Users who reach these limits may purchase extra session packs; packs are valid for 90 days from purchase, are exempt from the daily limit, and do not auto-renew (an active subscription is required to buy them). Abnormal usage via automated tools or account sharing may lead to suspension of the service.

4. Refunds and withdrawal

The digital service is delivered immediately at the moment of purchase; by confirming at checkout you consent to immediate performance, and where applicable law provides a withdrawal exception for instantly delivered digital services, that exception applies. You may cancel your subscription at any time; access continues until the end of the current period and no partial refund is issued. If you are not satisfied within the first 14 days, you may request one full refund per account. Upon refund, granted benefits (credits, minutes, gift codes) are revoked.

5. Content and intellectual property

Lesson content, voices, and platform software belong to Derso and may not be copied or distributed outside personal learning. AI-generated content may contain errors and is not professional advice.

6. Certificates and exams

Level exam results and certificates are issued under derso's own assessment criteria and are not official or accredited documents.

7. Limitation of liability

The service is provided as is. Derso is not liable for indirect damages from interruptions or content errors; mandatory consumer rights remain reserved.

8. Changes and termination

Terms may be updated; material changes will be announced. You can close your account at any time from Account -> Delete my account.

9. Governing law

The service is operated by Derso, a company established in the United States, and these terms are governed by U.S. law. However, nothing in these terms limits the mandatory consumer protection rights of your country of residence.