At the end of last year, Microsoft killed off its Groove Music Pass service. The Groove apps themselves continues to function as a way to stream music that's stored in users' OneDrive storage, and as the default player on Windows 10 (you still can't even uninstall the app).
But today, Microsoft announced that it will be retiring its Groove Music apps for iOS and Android on December 1. The news comes from a support document that the firm posted today, which says that even if you have the apps installed, they will cease to function after that date.
This only applies to the apps that are made for iOS and Android, as the Groove apps for PC, Xbox, and Windows phones will continue to function normally. Of course, it's not beyond Microsoft to leave an app in Windows 10 as useless, despite being unable to remove it. The Messenger app is a prime example of this, as it was originally made as a Skype client and later for SMS, but neither of those things work anymore unless you have an LTE-enabled PC.
If you store a lot of music in OneDrive and you like to play it back through your phone though, it looks like you'll need to find another solution within six months.