I'm not an expert on the subject (especially the legal stuff), but if I already payed for listening to a track on Spotify and I can hear "Like a stone" by Audioslave, then why should I not be able to see the tab?
1. Does the current user own a subscription to any of our registrered streaming service?
1a. No: Go to the "Sorry, no access for you-page
1b. Yes: Is the song "Like a stone" by Audioslave available for the current user on the current streaming service?
1b1. No: Go to the "Sorry, no access for you-page
1b2. Yes: Show the tab
Are there different legal rules for recorded tracks and tabs?