Guideline 3.1.1 - Business - Payments - In-App Purchase

Guideline 3.1.1 of the App Store Review Guidelines states that apps must use Apple's in-app purchase system for all digital content and services offered within the app. This means that any purchases of digital goods or services, such as subscriptions, premium content, or virtual currency, must be made through Apple's payment system and subject to their commission fees.

There are some exceptions to this rule, such as physical goods or services that are delivered outside of the app, but it's important to follow the guidelines closely and consult with Apple if you have any questions or concerns.

Overall, the purpose of this guideline is to ensure a level playing field for all app developers and to maintain a consistent user experience for customers across the App Store.