I have heard from friends that they got banned for using adblockers on free Spotify. I used a tool, forgot what it's called, for the brief time I had Spotify Premium where you could give it access to your account via the API and it'd search music piracy websites to download all the songs and albums in your library. After I had downloaded my library I cancelled my subscription. So that was entirely within Spotify's ToS. (Music piracy is still illegal, but the violation didn't happen against Spotify.) I suppose if you wanted to do this then doing something like that, where you just look the song up on music piracy sites and don't actually download from Spotify directly, would be less likely to get your account banned. You still need Premium to access the API, but you could just scrape the webpage if you want.