TLDR: It's now completely free.
Originally, I was using my own event system for a game I was making. Because of reasons with poor back-ups I couldn't continue with it and I don't really feel like starting over right now.
Because of that, I was also no longer working on the event system. This meant it would frequently also not compile any more AND my paypal account was also closed because I moved to a different country (and no longer use paypal for anything anyway..).
On top of that, I also felt bad about charging money for a project that did not compile out-of-the-box. A small thing perhaps, but all reasons combined made me decide to make it now free for everyone.
A big thank you, to everyone who bought it over the years. I really appreciate the support you gave me and I hope you're all doing well!
Enjoy the event system, I hope it can be of help to a couple of you here.