I have two accounts with the same name

[lareina]

I signed up for 3 months of free spotify premium through optus perks on my phone. The 3 months is now up and I'm paying for premium, but when I sign into spotify on my laptop the account comes up as the free version and always has. I haven't signed out on my phone as it has all of my playlists on that account and I'm scared that if I do I'll lose them somehow. I'd like to know how to join the two accounts together. Thanks!