What do I do when I terminate my third party subscription and they will close my Spotify Premium??

[Spotifiable]

Dear Spotify Crew and Users all over the world,

I have a Dutch KPN subscription which allows me to use the Premium version of this great app.
Please tell me how I can make sure I don't loose al my playlists I have created over the years when I terminate the contratc with KPN.

Looking to sign in on a family account for me and my girlfriend so she doen't have to use the free version anymore.

Kind regards,

Spotifiable!