Spotify is a music streaming service that is available in a big part of Europe and USA. The software itself consist of different versions: a free – “Open”, an “Unlimited”, and “Premium”. One of the big differences in-between these version is the advertising. The Open version contains advertising and a limited amount of listening hours. The Unlimited version is as Premium, but without certain mobile features. (Read more here…).
As Financial Times reported, the amount of premium users has grown from 15% to 20% in Mars 2011, which means ca 2.5 million premium users.
More about spotify at spotify.com