YOU NEED TO HAVE BOTH APPLICATIONS INSTALLED, THE FREE VERSION AND THIS PRO KEY.YOU WILL NOT SEE AN ICON FOR THE PRO KEY.This is the pro key for the Chess PGN Master http://play.google.com/store/apps/details?id=com.kalab.pgnviewerIt removes the restrictions of the free version and adds an edit mode which allows you to:* try out analyzed lines* edit annotations* promote variations* delete moves and variations