Hello Rayna.
Well, it depends on what role you have in that blog you had the restriction on. s2Member can be used in multisite, but each blog in the network will be independent of each other, including the scope of s2Member’s restrictions and access. So if you have an account in one blog and try to view a restricted page in another blog, that could be the reason.
If you are logged in as the admin, s2Member should not be applying any restrictions to you, though. Make sure what account you’re logging in with, and where.
I hope that helps. :)
By the way, how do you plan to use the multisite network? I noticed you have a single site license for s2Member Pro.