Thank you for the quick answer. I'm a little confused right now, according to the documentation (https://developer.apple.com/documentation/storekit/skpaymenttransactionstate/deferred) the transaction state is not finished when it enters deferred state and I should wait for another callback that indicates the final status. However, it won't solve my problem. According to the customer, "ask to buy" was confirmed and money was withdrawn from her account. So either way, the app should have been notified about the purchase. We're always checking for new transactions when starting the app and we also got the "restore purchases" button with which all transactions are getting checked again. I will add a timeout to deferred transactions for the next release. Meaning, as soon as a transaction is deferred, I will finalize it and lock re-purchasing the IAP. After 24h, if I got no transaction telling me either the IAP was bought or not, I will unlock the IAP for purchase in the shop again.