Lemma

App support

Lemma Support

Lemma helps students master high-school physics formulas through bite-sized study, practice, and review.

App Store link will be added when the public listing is available.

Supported languages: English, Simplified Chinese, Traditional Chinese.

Contact

For app help, bug reports, purchase questions, sync questions, or privacy requests, email [email protected]. We aim to send a first reply within 2 business days.

Please include:

  • App version
  • iOS version
  • Device model
  • Short description of the issue or question
  • Steps to reproduce the issue, if applicable
  • Screenshots, if applicable

FAQ

How do I start a study session?

Open Lemma and choose the formula topic or review area you want to practice. Start a bite-sized study, practice, or review session from the available options. If you are unsure where to begin, pick the topic you are currently studying in class and review the basics first.

What does Lemma Membership include?

Lemma Membership includes the member features shown in the app, such as any premium study, practice, review, or sync features available in your version. The exact feature list may vary by app version and region. Membership is managed through Apple's App Store subscription system.

How do I subscribe? What payment methods are supported?

You can subscribe from the Lemma Membership screen or another in-app subscription offer. Purchases are processed by Apple through the App Store. Supported payment methods are the payment methods available for your Apple ID, such as card, Apple Account balance, or other local App Store options.

How do I cancel auto-renewal?

You can cancel in iOS Settings → Apple ID → Subscriptions, or at https://apps.apple.com/account/subscriptions. Select Lemma Membership and follow Apple's cancellation steps. To avoid being charged for the next period, cancel at least 24 hours before the renewal date.

How do I restore a previous purchase?

Use Restore Purchases from the subscription offer screen or the Settings → Membership screen in Lemma. Make sure you are using the same Apple ID that made the purchase. If the purchase still does not restore, contact support with your app version, iOS version, and device model.

How does iCloud sync work? Where is my data stored?

When iCloud sync is enabled, study data is stored in the user's private iCloud container via Apple CloudKit. Lemma does not run a study-data server. Sync availability depends on your Apple ID, iCloud settings, network connection, and Apple's iCloud service.

How do I delete my data?

For local data, use the in-app Reset option if available, or uninstall Lemma from your device. For iCloud data, use iOS Settings → Apple ID → iCloud → Manage Storage. For a formal request, email [email protected] with the subject "Data Deletion Request". We will respond within 30 days.

What devices and iOS versions are supported?

Lemma supports the iPhone and iOS versions shown on its App Store listing. If Lemma is offered for iPad in the App Store, iPad support follows the availability and version requirements shown there. Device availability may vary by app version and region.

Privacy and Data Requests

To exercise privacy rights, including access, correction, deletion, objection, or portability under GDPR, UK GDPR, CCPA/CPRA, or other applicable laws, email [email protected] with the subject "Privacy Request". We will respond within 30 days or as required by local law.