Register page show fatal error message

Hi there,

I am trying to setup my membership plugin so user can sign up and become member. However, after installing membership plugin, register page has been created by the plug-in, but when I click on it, it show fatal error message below.

"Fatal error: Call to a member function has_subscription() on a non-object in /home4/enoch/public_html/leapaccelerator.com/wp-content/plugins/membership/membershipincludes/classes/membershippublic.php on line 1584"

Can you please help me check on what the problem is?

Thank you so much for your help!

Enoch