官方给出解释:
消费类每次购买后, 同一个key对应的属性会编程owned, 你必须消耗掉这次购买, 才可以继续进行购买
原文:
In Version 3, all in-app products are managed. This means that the user's ownership of all in-app item purchases is maintained by Google Play, and your application can query the user's purchase information when needed. When the user successfully purchases an in-app product, that purchase is recorded in Google Play. Once an in-app product is purchased, it is considered to be "owned". In-app products in the "owned" state cannot be purchased from Google Play. You must send a consumption request for the "owned" in-app product before Google Play makes it available for purchase again. Consuming the in-app product reverts it to the "unowned" state, and discards the previous purchase data.
http://developer.android.com/google/play/billing/api.html#consume