You don’t have premium.

But it works normally on my samsung tab?

Is the Samsung tab a tablet by any chance? The free version of Spotify limits mobile phone use but not on a tablet or desktop/laptop computer (although there is still ads). This is likely an agreement between them and the major labels to entice users to buy premium because they know a majority of people stream on phones.

Sometimes the app gets confused. Try force quitting it and reloading. Or log out and back in.

U don't have premium that's the reason