Fatal error: Call to undefined method

I down loaded and installed the paid version of membership plug in ... I am running wp Multisite and I got this error when I went to activate ... I don't have alot of experience coding so is there a simple solution.

Fatal error: Call to undefined method stdClass::set_help_sidebar() in /home/content/15/6807515/html/sems_areas/wp-content/plugins/membership/membershipincludes/classes/class.help.php on line 73