I just bought the license for the full app. I have tried opening it with the app, but I keep getting the “trial period has expired” dialog.
I have followed the instructions here: https://www.glyphsapp.com/tutorials/how-to-install-your-glyphs-license
One note is that I do not seem to have the ByHost folder in my library. Is that a clue?
Nevermind! I restarted a couple more times and clicked the license and closed and clicked and closed and clicked again, and then I got the thank you message. All good now 
Very unlikely. On more than one occasion, people have said to me that they wouldn’t have a ByHost folder, but they did. If these problems happen again: Are you looking in the right library? Perhaps copy and paste the path in the Go To dialog (cmd-shift-G).