spotifyThe Swedish music streaming giant Spotify just hit a milestone: its 10 millionth premium (paying) customer. Add that to its collection of listeners (both paying and non), and the company has more than 40 million current users. That’s a lot for a private company that is still getting its feet wet in America.

This is a pretty big surge for Spotify – the last time it released its numbers, it had just 6 million premium customers and 24 million active users worldwide. That’s a huge jump.

Those who sign up for a premium account get a lot for their $10 per month. Non-stop access to tons of music (which includes the option of uploading music they don’t have the rights to), personally made radio stations and the ability to see what music friends are enjoying listening to. Plus, Spotify plays right into many users’ love for nostalgia with a feature that allows users to make “mixed tapes” for their friends.

Spotify allows users to create their own playlists.Spotify allows users to create their own playlists.

Spotify allows users to create their own playlists.

At $120 per user per year, that’s $1.2 billion in revenue, and that’s not even counting the revenue from advertising that is targeted toward all non-premium users. Add in the money made from corporate deals like their current ones with Sprint and HTC, and you can say they have a pretty bright future ahead.

Rumors about Spotify going public have been swimming around for a while, but CEO Daniel Ek is keeping his plans under wraps. He’s also not saying anything regarding the purchase of “Beats by Dre” by Apple, which is hoping to become Spotify’s number one competition. But Ek doesn’t need to say anything – the popularity among customers seems to be speaking for itself.