Upgrading to Premium

[chapel]

I have purchased the Premium version and attempted to install it but am getting a Fatal Error message:

Fatal error: Cannot redeclare InstallScript() (previously declared in /var/www/chapel-test/wp-content/plugins/appointment-calendar/appointment-calendar.php:33) in /var/www/chapel-test/wp-content/plugins/appointment-calendar-premium-3.6.5/appointment-calendar.php on line 17

Any ideas?