When you match and download files from iCloud Music Library (without having an iTunes Match subscription), however, you get files with DRM; the same kind of files you get when you download files from Apple Music for offline listening. (These files should have DRM, so you can’t just download and keep all the music you want for $10 a month.) But if you’re using Apple Music, and not iTunes Match, Apple doesn’t make a distinction between which files were originally yours, and which you downloaded for offline listening from Apple Music.
If you plan on making use of iCloud Music Library, be sure to keep copies of your original files. Otherwise, you’ll be stuck paying for Apple Music indefinitely or risk losing your music library all together.