The full rule > Payment is for digital content that may be consumed outside of the app itself (e.g. songs that can be played on other music players). As Spoti

The full rule > Payment is for digital content that may be consumed outside of the app itself (e.g. songs that can be played on other music players). As Spotify music can be used outside the Goole Play app, Google doesn't take a cute. The same reason I can buy Kindle ebooks within the Android app