Google doesn't collect a paid license fee for Google Apps on Android, but they have fairly significant nonmonetary agreements, essentially barring the OEMs from using Google's competitors, making Google's products the default, dictating where Google Apps must be placed on the home screen, etc.

Some of the larger OEMs might be able to negotiate revenue sharing agreements from Play purchases, but inside the Google Apps is definitely where Google makes its money, on app sales and ad targeting based on data collected by Google hoovering up everyone's mobile data and location.