This extension is used for paid membership / paid customer group ... you can give special discounts to paid groups . If your membeship expires then you'll be upgraded to default group.
check demo here:-
Admin :-
https://demo-opencart.com/membership/administrator/ ( admin / password )
Front end :-
https://demo-opencart.com/membership/
For any other opencart extensions or help add me on skype: aditya_web or email me at [email protected]