There is no other server associated with this app, so iCloud is the only thing available to try to work out with. The link
https://developer.apple.com/library....html#//apple_ref/doc/uid/TP40008267-CH5-SW16
describes (below) a way to save a receipt in User Default or iCloud. Perhaps this receipt can also be verified from user's other devices. How can this be done in B4i?
Persisting a Receipt in User Defaults or iCloud
To store a transaction’s receipt in User Defaults or iCloud, set the value for a key to the data of that receipt.
#if USE_ICLOUD_STORAGE
NSUbiquitousKeyValueStore *storage = [NSUbiquitousKeyValueStore defaultStore];
#else
NSUserDefaults *storage = [NSUserDefaults standardUserDefaults];
#endif
NSData *newReceipt = transaction.transactionReceipt;
NSArray *savedReceipts = [storage arrayForKey
"receipts"];
if (!receipts) {
// Storing the first receipt
[storage setObject
[newReceipt] forKey
"receipts"];
} else {
// Adding another receipt
NSArray *updatedReceipts = [savedReceipts arrayByAddingObject:newReceipt];
[storage setObject:updatedReceipts forKey
"receipts"];
}
[storage synchronize];