Free 4 Month Google Play Music and YouTube Red Subscription (New Subscribers) | Google
This deal is back again! You will be charged after the 4 month trial is complete. However I can confirm that you can immediately cancel after you sign up and your subscription will end automatically after 4 months. So probably do that just to be safe.
Although it says new subscribers only, if you haven't had a Google play music subscription for over 12 months you should still be able to sign up for this one.
Deal originally found here.