Fade In stores some information in a special folder on your computer. This includes things like dictionary files, autosave backups, shortcut key mappings, system reports, and other things (but not document files).
Press the Windows key, then R to show the Run window. Then type:
and hit Enter. That will bring up an Explorer window with a number of folders in it. One of them will be called Fade In. Double-click on that.
Note: %APPDATA% is a shortcut for C:\Users\<Username>\AppData\Roaming.
From the Finder, choose Go > Go To Folder, and type:
~/Library/Application Support/Fade In (don't forget the leading "~")
For the Mac App Store version you'll need to type:
~/Library/Containers/com.generalcoffee.fadein/Data/Library/Application Support/Fade In
~/.fadeinTags: backup, dictionaries, logging, shortcut keys