How does a device manufacturer license Google Play Services (GPS)? I mean the system library that is required by many apps, I do not mean Google Mobile Services (GMS) which includes GMail etc. (although it could be possible that you have to license the latter to get the former). And what does it cost?

Are there other requirements, for example, do you need to pass the compatibilty test suite (CTS)? Does that cost anything? I read that “Android compatibility is free, and it’s easy”, although I recall reading somewhere else that it costs several tens of thousands per device and ROM version because you have to be tested by a licensed shop.

Similarly, if a GMS license is required: I read that Google “does not charge license fees for Android’s Google Mobile Services”, but somewhere else I read that it is expensive, too. Also I read that if you produce one device with GMS, you must ship GMS on all devices without exception – with the intent that you cannot slowly move away from Google one app at a time. OTOH, Chinese manufacturers do sell versions with and without Google legally.

It would be great if somebody could provide an answer like “it’s free, just download it” (offical statement) or “you need to do X, Y, and it costs $ Z per device. Contact Google here”.