Do you mean Network data or actual storage on the device? If the former, because I use Spotify premium, most of my music that I listen to is within offline playlists. I mostly search for new music when using wi-fi.
I was referring to the network data. I thought that if a song was 10mb, it would take 10mb worth of data usage to listen to it. After reading these replies, I'm thinking I'm in error since so many people do it.
So with Spotify you download the song into your device to listen to later?