Restore in-app purchases for different app accounts

I’m implementing in-app purchases (non-consumable) to my iOS app, and I’m stuck with restore purchases. When a user registers in my app, I create a user account (A) on my server. After the user buys an in-app purchase, I need to tie the account and iIAP (A+IAP). The question is - what if the user creates a new user account (A1) and restores the IAP? Will it unlock premium content for another user? (A1+IAP). If yes, how to fix that?