Spotify is removing several key restrictions on its free accounts and will now be available without charge on mobile devices, albeit with one major limitation. It’s also agreed to license tracks from Led Zeppelin, one of the most notorious digital music holdouts.

The first change is that free accounts will no longer be subject to a 10 hour per month limit: as was the case when the service launched, free users will be able to listen as much as they like.

The other changes affect mobile users. Those listening on tablets (defined as the iPad, iPad Mini and any Android device with a screen of at least seven inches) will get the same access as desktop users, with the ability to play any tracks in any order. As with desktops, there’ll be ads every 20 minutes or so. Tablet listening will work the same whether you are on Wi-Fi or cellular connections.

Smartphone users will also get unlimited listening without the need for a paid account. However, those on free accounts won’t get complete control over the order that tracks are played. Instead they’ll have two options, known as free shuffle mode:

• Pick an artist and have all of their tracks played in a random (shuffle) order. This differs from the existing “radio” function where you pick one artist but get music from related artists as well.
• Pick or create a playlist and have it played in random order. To play this way, a playlist must cover at least 20 different tracks from three different albums.

There’ll now only be one paid account, with Spotify dropping a mid-range option that removed the ads and listening time limit. The premium option, which remains at $9.99 a month in the US now has fewer advantages, notably no ads, better audio quality over cellular connections, the ability to listen to tracks in any order on smartphones, and the ability to cache songs on your smartphone for offline listening.

On paper the changes could hurt premium subscription sales. Spotify appears to be betting on something close to the original model by which making the free service more attractive will bring in more users, boosting ad revenue and increasing the number of people who get used to the service and may consider an upgrade.

The change also suggests Spotify has reached the point where the balance of ad rates and royalty payments mean free accounts are fundamentally profitable for the company.

Spotify has also agreed an exclusive streaming deal for the Led Zeppelin catalog. That’s notable as Led Zeppelin was always among the most common bands in the phrase “I like the idea of Spotify, but they haven’t even got anything by…” (That doesn’t mean you should hold your breath waiting for the Beatles however.) The Zeppelin albums are being added in chronological order, with the full selection scheduled to be available from Sunday.