BuddyPress Limit Group Membership plugin was conceived in the comments of my other plugin Limit Groups Per User. The BuddyPress Limit Group Membership plugin allows site administrators to limit the no. of groups a user can join. Yes, that includes the no. of groups a user can create. If you don't want to limit the no. of groups a user can join and just want to limit the no. of groups a user can create, please use Limit Groups Per User instead.
What It does:-
- Limits the no. of Groups a user can Join
A few screenshots:-
On group create:- 
As an administrator, you can set the no. of Groups a user can join by visiting Dashboard->BuddyPress->settings as shown below. 
Hope it helps you all the Social admins out there 🙂