Downloadify, a plug-in for Google's Chrome web browser, made it possible to download and store tracks from your Spotify account. It worked by creating a DRM-free back-up of any track you played in Spotify on your computer.
But as soon as it became popular among illegal file sharers it was pulled from Chrome's Web Store. It is available elsewhere online, should you look hard enough for it, but Spotify is also claimed to have closed the particular loophole Downloadify was exploiting.
Previously, Downloadify could be used to sign up for a month of Spotify and then just download all the songs you needed before cancelling the subscription. It's not known whether the developer of the plug-in is working on a second version that will work around Spotify's countermeasures.
Certainly, Spotify wasn't too happy about the plug-in. It negated the need for Spotify Premium, part of the streaming service which the brand is trying to push the most.
We also doubt that Downloadify was or is particularly legal, so unless you fancy risking a brush with the law, we don't recommend you even try to use it. Also Spotify is a brilliant service and the £9.99 monthly asking price for the unlimited offline downloads you get with Spotify Premium isn't exactly unreasonable.