Membership 2 - protecting single posts on a sub-site in the network

Hey. Okay. So ...

I've built a publishing company.

1) Into the Mythica is my MAIN SITE
2) Myth of Peter Fae is a SUB-SITE.
3) There are other sub-sites, for particular Authors; example: Myth of Dakota Chanel, Myth of Sun Marian

4) Each SUB-SITE has posts & pages which I want to be associated with the various levels of membership (I used the Bronze, Silver, Gold payment idea in Membership 2).

How do I set that?