Guideline 3.1.1 - Business - Payments - In-App Purchase
Your app uses intermediary currency to purchase items that function as non-consumable products but does not include a restore mechanism.
Users restore transactions to maintain access to content that they've already purchased.
To resolve this issue, please modify your app to include an optional user-registration feature that allows users to restore their purchases to all of their iOS devices.
We recommend indicating that account registration is necessary to restore previously purchased in-app purchase products and providing a way for users to register later if they wish to access this content in the future.