If spotify has free music, how do they get paid?
how do the workers get paid besides the adds
Spotify gets most of its revenue from ads displayed on their page and on radio. They also get some money from music purchases by partner retailers and their paid subscriptions. See en.wikipedia.org/wiki/Spotify#Revenue_model for more on the same.
The ads, of course, but they also have a 'premium' option that allows you to pay a monthly fee to not hear the ads (and also to listen 'offline', as in on your cell).