Aug 7, 2012
Google has recently clarified some of their developer rules on Android, particularly with advertising and in-app purchases.
Ad restrictions are tighter; now apps’ ads are considered part of the app as well, and content in ads that violates the Google Play Developer Terms will be cause to get an app rejected. As well, apps cannot install shortcuts or change system settings without explicit user permission.
The requirement for in-app purchases is tighter now, as apps “must use Google Play’s payment system as the method of payment.” This essentially locks out third-party payment processors from Google Play. Now, the policy is actually far more lenient than Apple’s, where nowadays even Amazon can’t sell books or movies directly through their apps. Google specifies that “where payment is for digital content or goods that may be consumed outside of the application itself,” then it can go outside of Google Play’s in-app purchases. Physical goods and services purchases are also exempt.
Source: Pocket Gamer