A friend of mine founded a startup and asked me to create an Android app for him. I did it with Java in Android Studio, but since I never developed a commercial app before, I have a few (related) questions about licencing.
For example, if I'm selling the app to him (without publishing it on Google Play) do I need to buy a Java license? Does my friend have to buy a license too? And do I need to put my app under my own license or his?