Microsoft will continue to run Groove Music Pass until the end of calendar 2017. After that point, those users with any remaining months of paid subscription to the service will be reimbursed. Starting this week, Microsoft will be encouraging those using Groove Music to migrate their playlists and music to Spotify.
Microsoft will continue to update the Groove Music application on all Windows devices, however, allowing those who have music stored in OneDrive to continue to play and manage their music through that app. But after December 31, 2017, the Groove Music app will no longer allow users to stream, purchase or download music.
Also see: Microsoft to bring Spotify to Groove Music Pass customers - Windows Experience BlogWindows Experience Blog and Groove Music and Spotify: FAQ.
Most importantly, note: Music will not be available for purchase or download from Groove after December 31, 2017. Thus, f you bought anything using Groove Music, make sure everything's been downloaded before the service is shut down.