Apple Music songs when canceling account and starting a new one
As long as the two Apple Music subscriptions are tied to the same iCloud account, your music will remain in your iCloud Music Library, and will all be accessible and playable once again after you sign up for a new subscription.

For instance, if you switch from a Family plan to a personal plan, your music should not disappear, so long as you don't delete the music from your iCloud Music Library.