Spotify plays a few songs shuts off/stops playing music after a few songs

[Viciouscupotea]

So I like to listen to music to fall asleep to, and I noticed when I lay down, turn Spotify on, put my headphones in, select my playlist, it plays maybe 4 songs maybe a couple more and it turns off. I have a cheap Android phone, ZTE lil ol prepaid straight talk phone, and I don't have premium Spotify yet. Could it be my phone or is it the Spotify app itself like maybe from not being active? I am Spotify all the way, don't get me wrong, I just never had this issue with Pandora (I just don't like Pandora as much as I do Spotify.) Please help!!!!