When a user purchases a subscription, I store the receipt on completed transaction on the server alongside a key to identify the user the receipt belongs to. When the app needs to check if the subscription is still active, it queries the server, the server validates the receipt with Apple and returns info to my app wether the subscription is expired or not.
Now the question is:
When the response returns a latest_receipt/_info field, the server should take that receipt and replace the old receipt for future verifications. What happens if there is a gap in the subscription period (e.g. the user subscribed for 1 month, then cancelled, then subscribed again) or the user changed the subscription type (e.g. from 1 month to 3 moths)?
Will the original receipt still validate, and return a latest_receipt/_info field, or do I need to store a new receipt from the new transaction?
I’m really confused on this auto-renewal thing right now, so I’m not even sure if my validation process is right.
I’m not sure about all possibilities you have to verify receipts and maybe it works your way, but we did slightly different and by that don’t face your problem.
We store all the receipts on device-side (note that auto-renews result in new receipts as well). Whenever verification is necessary we post the latest device-stored receipt to server where it is verified by calling iTunes. After that the server responds to device about user’s rights.
I think that’s the way Apple recommends it (or at least this is how I understood Apple’s docs).