It is not currently possible to purchase individual tracks from Spotify, since the downloads store has been removed. More information is available over on this help page.
What you are asking is a little bit of a grey area, and take into account here that I do not work for Spotify.
However, that being said, I have copied the first paragraph of section 4 of the Spotify Terms and Conditions of usage below:
4. Licence and assignment The Spotify Service and the content provided through it are the property of Spotify or Spotify's licensors, and we grant you a limited, non-exclusive, revocable licence to make personal, non-commercial use of the Spotify Service and to receive the media content made available through the Spotify Service in your Local Country, based on the Subscription or Trial you have selected (the “Licence”). This Licence shall remain in effect for a period of 20 years unless terminated by you or Spotify.
The keyword being "personal" since that is the only licensing Spotify has for tracks. Taking from that, public consumption of Spotify even if paying the extra licensing would still be in breach of the terms in my eyes.
If you would like a direct answer from Spotify, the best place to do that is to get in touch directly using the online contact form.