How to enable some extra functionality for paid app alone in android?

I developed one application. I planed to release that as a free app in market, also I want to add some extra functionality in a same app as a paid app. But I want to r开发者_StackOverflowelease only one apk in that, I have one button in a my free app, so user when click that it will show message like to enable this you have to buy this app. My problem is after the user bought my app I have to dismiss that message and enable that functionality within the my app as programmatic.Is it possible?, and How do I know user bought my apps?

Thanks,

Lakshamanan

You would need some server software (that stored your transaction/AppId) and confirm your users' payment validity from there.

There are also solutions from e.g. Paypal: http://www.mobilecrunch.com/2010/05/19/paypal-launches-in-app-payment-library-for-android/ . To my knowledge, there are no Android Market solutions for this, whose would greatly enhance this for you.

Have a search on StackOverflow for "[android] in app payment]".