Implementing In App purchases in Android?
This has changed as of today! There is now an example on the Android Developer site here: https://developer.android.com/google/play/billing/billing_overview
You can create a premium key application, that will have a key. How you expose that it's your deal ( or you can just check if PremiumKey activity exist ). From the main app you just check for your key and if it's exist enable premium option )If you're talking about buying OTHER apps from yours - build your list with market url pointed to the other apps ( market:// )
It is against the Android Market Developer Distribution Agreement to take in-app payment:
3.3 ... All fees received by Developers for Products distributed via the Market must be processed by the Market’s Payment Processor.