How Do I Limit A Plugin To A World?

I found an incredible Kit PvP plugin, but it breaks pvp on almost any other world. By that I mean you cant pvp unless you use the join sign. So I want to limit the plugin to just one world. I have seen several other servers do this kind of things and I tried it out but came up with some problems. My server is running at minecraft 1.8.9 with spiggot 1.8.7. I tried using PerWorldPlugin, but it never showed any effect in game, and never made the config folder, or anything. Almost like the plugin wasn't even on the server. Any ideas on why this happens, or are there any other plugins that restrict plugins to one world? Please help.