Great, thanks for the replies all

For the record the fix was easier than deleting the files and re-entering the license codes. I simply moved these four files from the root-level Library directory:

/Library/Preferences/com.LHRTechnologies.BoardEditor.plist
/Library/Preferences/com.LHRTechnologies.BoardEditor.plist.lockfile
/Library/Preferences/com.LHRTechnologies.PatternEditor.plist
/Library/Preferences/com.LHRTechnologies.PatternEditor.plist.lockfile

into my user Library:

/Users/leocp/Library/Preferences/com.LHR Technologies.Board Editor.plist
/Users/leocp/Library/Preferences/com.LHR Technologies.Board Editor.plist.lockfile
/Users/leocp/Library/Preferences/com.LHR Technologies.Pattern Editor.plist
/Users/leocp/Library/Preferences/com.LHR Technologies.Pattern Editor.plist.lockfile


Designer worked immediately with no need to re-enter the licence codes. I then set the permissions on the /Library/Preferences back to their default settings.