To keep it short: I'm not able to activate Groupy as clicking on "Enter Product Key" is not working - by "not working" I mean that simply nothing works, except the button animation. It might be a DPI-related issue: Having 3000x2000 with DPI 200%. When using the keyboard keys (tab and ENTER) I'm able to proceed with the activation. So at least for me it's no more issue. (I'm referring to following screen: https://s.pkern.at/2018-12-03_204910-qbz1d.png)

Furthermore: Some parts of the application seems not to be quite HighDPI-optimized. For example the activation dialogs just looks extremely small and is quite hard too read. Take a look here, to see the proportions of the UI: https://s.pkern.at/2018-12-03_205345-mg4fc.png 

OS: Windows 10 Pro 1809 x64 (November Update)
Groupy versions tested: 1.17 1.18