Why did my Apple Music Subscription not renew?

I've had Apple Music for quite a while now. I was listening to it yesterday. Today? My playlists and downloaded music to my phone is gone. All of it. It shows I no longer have a subscription and asks if I want to join. What happened? I thought this subscription was set up to renew every month until I cancel it. I never cancelled it. I joined Apple Music to prevent this sort of thing to never happen.

Can anyone tell me how to prevent this in the future? Is there a way to get it back on my phone?