having to download all songs every time I use Spotify

[Mcnamara171001]

hi guys can you help everytime I use Spotify I have to go to My Playlist and download all songs every time I need to use my playlist this has happened to me 8 to 10 times and it is costing me a lot of data every time I download it is taking up to 250 megabytes of my Internet allowance why should I have to continue to download My Playlist every time I want to play my playlist music