I have not modified the auth or payment system or anything else that would make a huge difference in the extension, the only thing i modified was the following part of the extension
-> js/page/gamePage.js line 1237
-> js/page/groupPage.js line 90.
(download an archived chrome version and compare the twos code if you wanna see what code have been removed)

They have asked me to remove these part of the code due to security reasons, this might have caused some stuff to not work properly so i apologize for that, but other than this everything else is untouched so the money you pay for it goes to the extension creator.
Tho i highly dont recommend buying a subscription if you want to use it on Firefox as it might not work correctly.