I could be wrong but it looks like the last time it was free for 90 days was back in 2015.
Offer not available to users who already tried Premium. Cancel anytime.
Steps to copy your existing playlist to a new account -
1) Make them public on your old account.
2) Sign into your new account.
3) Search for you old username.
4) When you find you old account and public playlist(s) copy all the songs into a new playlist(s).