Spotify does not use P2P (confirmed officially), still music consumes a lot of data if it is played in high quality since high quality obviously needs more kilobytes. The data consumed by different quality songs are: 96 kbps Quality - 0.70 mbps. (This quality is available on mobile only) 160 kbps Quality - 1.2 mbps (This one is the free quality and is also very good for listening songs) 320 kbps Quality - The best quality that spotify supports for now and is only available for premium users, this quality is also available in desktop. You can download the songs one time so that your data may not be consumed every time you listen the same song or play same songs in a queue, so we recommend them to save in the offline space in your device. BTW there is no need to worry about data if you already have a Wi-Fi plan. Spotify premium also provides you with unlimited bandwidth. People prefer online song streaming rather than downloading them.