Microsoft's Groove Music service bowed out months ago, but all the apps have been available for listening to your personal files... until now. The company has revealed that its Android and iOS apps will disappear from their respective online stores on June 1st, 2018, and the apps themselves will be "retired" (that is, stop working) on December 1st. After that, you'll have to use OneDrive or migrate your songs elsewhere to keep listening in the cloud.
The Windows 10 apps for PCs, Windows-powered phones and Xbox One will continue to work for your personal collection, so this isn't a complete shutdown of the software. However, there's little doubt that Microsoft is reducing Groove Music's support to the bare essentials. Now that it has effectively conceded to the likes of Spotify and Apple Music, there's not much point to maintaining apps across platform.