Keeping your mobile apps free to download but then unlock features based on users choice can greatly increase your sales. This is a well known fact but considering that you are developing your application with Adobe AIR, you are expecting to have an in-app-purchase API which works equally on both Android and iOS. Soon you will learn that although in-app-billing ANEs has been developed for a long time, none of them was able to provide you with a 100% identical API on both platforms.