Music streaming app Spotify learned that a number of users were accessing the full range of its services for free by using modified apps. These apps allowed users to essentially have paid Premium Spotify accounts without having to pay. However, Spotify is now cracking down on those users and modified apps, which may be part of the company's efforts in preparation for its IPO.

While users can still access the music streaming service for free, there are some limitations. Users with free accounts have to endure intermittent advertisements in between songs, and they also have shuffle-only play. This means that free account users will not be able to listen to songs in an album or playlist in order, and they will also only be able to skip songs a limited number of times.

However, users of the modified apps can access features behind Spotify's paywall for free. They simply have to download a modified app and enter their Spotify account details.

As first reported by TorrentFreak, Spotify has been sending an email about "abnormal activity" to users of the modified apps. The email advised users to uninstall the modified app and reinstall the official Spotify app instead. There was also a warning that continued use of the modified apps may result in the termination of the users' Spotify accounts.

TorrentFreak also reported that some users with modified apps can still log in, while others no longer can.

As of Dec. 31, 2017, Spotify has a total of 159 million active users. 71 million of these users are paying subscribers.

Spotify also sent a notice to software development platform Github, asking for the removal of a Spotify mod called "Dogfood." The site removed the mod on March 1, a day after Spotify filed for its IPO. It is speculated that these recent efforts to crack down on errant users and app modifications is Spotify's way of making sure that it will be able to attract investors.

Users of the modified apps may still attempt to log in, although they may be doing so at their own risk. There is a chance that these users, should they continue using modified apps, will eventually be locked out of their Spotify accounts and thus lose their playlists and personal music catalogs.