Membership plugin - can registrations be disabled on Subblogs?

I am using the membership plugin on a subblog and have Buddypress on my multisite...

Is there a way to also disable registrations on subblogs, rather from the network admin?

That way the membership plugin can be used on subblogs for various products without having to create a social profile on the main site (or worse, they try and register again when purchasing a membership)