Should in-app purchase restore be implemented when it is not useful for auto-renewable subscriptions?

I'm implementing an app that let users subscribe for extra storage to upload content. This is a monthly subscription and it is implemented as an auto-renewable subscription. An in-app purchase receipt will be used only once to confirm the purchase is successful and to get details like expiry date. Then the database is updated continuously with server-to-server notifications.

However the app got rejected since Restore is not implemented. I simply added a restore button along with its functionality. But I don't know what to do when the restore is successful.

For the scenario in this app how does transaction restoring can be useful?
Should in-app purchase restore be implemented when it is not useful for auto-renewable subscriptions?
 
 
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