Andrew Nevins on "Starting at level zero selling"

Made a vanilla JS gallery and want to convert it to a WordPress plugin for free and premium. I am a little lost on some things.

I searched around for a proper WordPress plugin tutorial but they all seem from back in 2014 and below and I know WordPress gets updated numerous times. So I am wondering if there a 2016 quick and dirty tutorial to get my plugin up and running?

Also, how do you license these things? Yes, I know about the GPL I mean how do you apply it to a digital product on your site and administer licensing codes?

Or should I just post a simple price and damn the license?

Also, does WordPress.com let you use plugins or do I need a real WordPress site that is web-hosted to do it?