If you want it to work like that plugin, you simply need to look at how that plugin does what you want it to do. This is the Scripting Help forum meaning that you are the one writing the plugin. You have all you need in the Hook plugin to implement the +command feature that you're asking for.
Try using the hook plugin as a basis and create your own plugin for your feature. If you run into a specific issue, post your latest version of the code with a specific question. It should be quite simple actually. If your code above works as you want functionally, simply replace the button check with a boolean check that gets set by the +/- commands.
Regarding the "permanent access", that's a whole different thing. You can find other plugins that save things like this (e.g. using nVault). So, after you get the main plugin functions working, start working on this part and post a new thread if you have specific issues.