Won't let me listen to music after premium trial is over

[Lames11]

So I tried out for the premium trial on Spotify.and then after my trial is over if my music was no longer highlighted green but when I tried to click it and listen to the song it would not let me listen to the song and I want to know why what did the premium do for this to happen to my music because before when I didn't try out for the premium trial I could click on my songs and listen to them whenever I want when I was connected to the Internet but now after I tried to premium trial I can no longer do this when and then after my trial is over if my music was no longer highlighted green but when I tried to click it and listen to the song it would not let me listen to the song and I want to know why what did the premium do for this to happen to my music because before when I didn't try out for the premium trial I could click on my songs and listen to them whenever I want when I was connected to the Internet but now after I tried to premium trial I can no longer do this why ?

[MattSuda]

Go into the settings and make sure "high quality streaming" is turned off