Sets up a "master player" list, and if people from that list are not online (or, optionally, OPs), other players cannot stay on the server.

It'll likely work on any version 1.8 through 1.19, I only checkmarked two as those are the only ones I used during my testing. I'm not taking the time to test 13 different versions, lol, I'm too busy for that

See the Documentation tab for instructions on how to use this.