Looks like it is a paid CMS. Is it much different from Grav and Pico? I have used Pico for a project and it is amazing.
We use it for many websites, its something hackernews people will not like but its fastest way to make small-medium size websites i know of.
administrate is easy, you can actualy easily build the admin interface so nobody can mess it up (compared to worpress that everybody breaks)
to make website - you have to do some coding
Great APIs and a really good documentation.
With a little bit of coding it went really fast and well.
Edit, to answer (from the docs):
There's no validity check of your code or any other communication between your Kirby installation and the Kirby server. You get a clean installation without any hacks or tricks. Entering the license code is for your own records, so you can track which installation uses which license.
I'm focusing on making Kirby better instead of fighting software pirates. I trust in you to support me with a legally purchased license if you like Kirby.