The first wave of Apple Music trials will be expiring soon and if you haven't subscribed for real it means saying so long to any Apple Music added to your iTunes library.
But as Kirk pointed out a while back, there may be some residual files left over in the ~/Library/Caches/com.apple.iTunes/SubscriptionPlayCache/ folder, which is sort of like an "iTunes Media" folder for Apple Music. It stores the specially protected audio files that are downloaded when you play a track from Apple Music on your Mac, ostensibly so iTunes doesn't have to re-download them if they are played again. They can't be user-played and are only useful to Apple Music. (This cache folder doesn't apply to Radio music. Or to Apple Music you've added to your library for offline use, which is stored in your official "ITunes Media" folder.)
I'm not sure if these files will disappear when the trial ends for you. iTunes doesn't appear to remove them even now, so if you've used Apple Music a lot then this folder will be loaded with quite a number of full-sized audio files. I'm a sucker for some of those "For You" playlists and I've managed to get my own cache folder up to about 7GB.
Flush Apple Music Cache Files is a simple script that will show the number of files in the cache and the space they take up and, if you wish, delete them:
And if you're subscribing to Apple Music and are tight on drive space, you can flush all you want anytime. Apple Music will re-download any music it requires again later.
Download the script from this page.