For Premium Geocoding, you don't need to buy it if your device already has a builtin Geocoder engine. You can try it by registering points /marker on the map, if the marker already contains the address data: you already have it. Some types of Android devices are not equipped with this Geocoder, if you really need them then you are required to buy Premium Geocoder.
We adopted the "In APP Purchase" model to manage premium features, it means that users must register themselves to be premium users and pay annual fees at very affordable prices (starting from around USD 0.9 / 3 months to USD 1.9 / year). Permium users can unsubscribe at any time without any conditions or fees. All the payment, refund etc.. will be handled by Google Play.
To be a premium user, you don't need to download a new application or APK file, just click the Buy Premium menu and choose the type of premium that you want from the list according to your need.
We try to make this application as free as possible, almost all the features in this app are free and can be used wihout any limit, except for some features that are provided by third parties and require server costs such as elevation data (msl) with high accuracy, geocoding and direction route.