Microsoft has changed the terms of its Zune Pass subscription service, allowing subscribers to keep some tracks each month as part of their permanent collections.

The company also announced that it will soon offer over 90 percent of its music in MP3, a format that does not come with DRM (digital rights management) restrictions. Microsoft's Zune player launched in the US two years ago, but is not yet available in the UK.

Until the changes were announced today, the Zune Pass subscription service gave consumers unlimited access to millions of tracks for $14.99 (£10) per month. But the tracks were rented to users, and their access to these tracks lapsed if they discontinued the service.

Starting today, subscribers will be able to select 10 tracks per month to keep and add to their permanent collections, which is an estimated $10 value, according to Microsoft. These tracks can be burned to a CD or moved to other devices even if the subscription ends.

The new subscription model is the outcome of agreements signed by Microsoft with top music labels such as EMI Music, Sony BMG Music Entertainment, Universal Music Group (UMG) and Warner Music Group, as well as independent distributors INgrooves, Independent Online Distribution Alliance and The Orchard, the company said.

Zune Pass subscribers will be able to retain MP3 tracks from Sony BMG and UMG, in addition to MP3 tracks from EMI Music, Warner Music Group and a large number of independent music labels, Microsoft said.

With the addition of tracks from UMG and Sony BMG, Zune will soon be able to offer over 90 percent of its music in the MP3 format, the company added.

Microsoft is also offering a free, 14-day trial to new customers to the Zune Pass subscription, but the facility to retain 10 tracks permanently is not available to customers using the free trial.

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