Just found your plugin today, played around with it and love it. So I purchased an upgrade and when I entered the key it produced a Fatal Error. Here's the full message I get.
Fatal error: Call to undefined function mcrypt_decrypt() in /var/www/vhosts/wroxhamtla.org.uk/httpdocs/wp-content/plugins/kontrol-developer-kit/app/classes/Admin.class.php on line 271
I would be really grateful if you could help me out here. Hopefully it's something simple.
Also, I've just checked the Admin.class.php file and it's the path_check() function that's producing the error.