I hope all is well for everyone, I have an app offering auto renewing subscription. Problem is I can't seem to figure out what they want me to do with it, I offer optional registration in order for users to access the paid subscription across all devices, but in their policy they require all auto-renewable must be accessible across all devices. But the other problem is they also don't want me to force users to register. My question is how can we be able to keep track of the subscription across all devices without tying it into an account? Did I miss something? any help is greatly appreciated.
App rejected due to reason: To resolve this issue, please make it clear to the user that registering will enable them to access the content from any of their iOS devices and provide them a way to register at any time, if they wish to later extend access to additional iOS devices.
Please note that although guideline 3.1.2 of the App Store Review Guidelines requires an app to make subscription content available to all the iOS devices owned by a single user, it is not appropriate to force user registration to meet this requirement; such user registration must be made optional.
Subscriptions are tied to a user's Apple ID. So, even without you registering them into your own account system, their subscriptions already are tied to an account.
If you use the StoreKit system for restoring purchases (https://developer.apple.com/documentation/storekit/in-app_purchase/restoring_purchased_products), the device will get any subscription/purchase data for your app that was done on any device with their Apple ID.
This means that on your subscription page, you can (and should) offer a restore button will allow users to get their subscription data on that device (whether it is from a different device or perhaps even the same device that was reset).
You can also choose to link it to your own account system, but that's all optional, since everything's already linked to their Apple ID.