Last December, Plex announced that it would bring its service to Kodi through the use of an add-on, enabling Kodi users to access to their Plex server. That was awesome news except for the caveat, if you wanted to use the add-on, you had to be a Plex Pass subscriber. Now, it appears that the requirement for a Plex Pass appears to have been quietly removed albeit with some features that remain unavailable if you don't have a subscription.
While Plex has its own media player designed for TVs, certain people prefer Kodi for media playback on large screen devices. The official add-on gives you the best of both worlds, eliminating the need to switch between the Kodi and Plex apps on your device.
The missing features, which are only available in the premium pass subscription, are audio fingerprinting, support for multiple user accounts, and parental controls, but if you are using the service currently without those features, then the fact you can integrate Plex seamlessly into Kodi at no cost will be of benefit.
Source: Windows Central