Spotify launched in the US nine months ago with the promise of a six-month period of ad-supported unlimited music but that time has since come and gone without any acknowledgement. Today the growing music outlet has announced that they are extending their unlimited free listening offer for an undisclosed length of time.

The original plan was for Spotify to limit free listening to 10 hours per month after the initial six-month welcome phase. One must assume that the overwhelming success of the state-side launch had something to do with the new course of action.

In January, the company announced that they had 3 million paid subscribers across the 12 markets it currently operates in. This equates to more than 20 percent of their active user base and was credited to the recent Facebook integration and month-long free premium trial subscriptions. Even more interesting, nearly half of the paying customers are under the age of 30, an age group that is traditionally hard to monetize.

Spotify offers three levels of membership. The free program allows you to listen to millions of tracks on your desktop albeit with some restrictions like reduced audio quality and ads. For $4.99 per month, you can ditch the ads and for $9.99 each month, you can access the service via your mobile handset and listen in offline mode, all with high quality streams.