In rare circumstances, the message "Invalid serial! Please contact the support." is displayed when registering LightLogger Keylogger with a paid license key. If LightLogger does not accept you paid license key, report the problem using LightLogger's Support feature in the Help tab. For instructions, see How do I use the Support feature in the Help tab? You can also report the problem by emailing HeavenWard Support at firstname.lastname@example.org.