TheWyrm Thanks for your reply. I read something like Google is changing unmanaged product to consumable managed product, do you know how this will affect us? I have tried to list a product as unmanaged product, did the purchase(Google charged my credit card), but the "On product purchased complete" event did not trigger... Managed product seems to work fine, but I did not try purchasing it multiple times. BTW, even when sandbox mode is enabled, Google is still charging me for purchasing the product...