How to unlock iphone game using prime31 storkit plugin?

Hi,

I am nearing completion on my first iPhone/iPad game and I am trying to implement the prime31 StoreKit plugin, although I could use some help... I've tried to figure out something from the pretty poor documentation, and googled a lot, but I can't really find some type of "first user guide" that in simple terms explains how to setup the plugin, for someone who's never attempted something like this before.

I dont want to do something fancy. I provide a free version of my game, with a simple "unlock" button, and when tapping that button I want the user to be able to make a purchase, and just change a playerprefs variable to "unlocked" (I assume that is the easiest way to do it?). And thats it, thats all I need.

I would be very grateful if someone who has done something like that could just either explain to me how to get started, or point me in the direction of some type of good and simple information on the subject.

I get that you need to set up a lot of stuff with iTunes Connect and so on, but what I am asking for is firstly some advice on how to use the prime31 plugin. What methods to use, and how to implement them, etc.

Thanks in advance!