Yes, now you're making more sense. So your basic "issue" (as I see it) is that not everyone will be signing up on the same day, etc. etc., so you want to keep the "newbies" from accessing whatever the 5th week people are on, right? I get it.
Part of me thinks that you're "overthinking" this - no offense meant! :) Possibly using the wrong terminology - and that's what's confusing me. The thing that's throwing off your explanation is the word "theme". For WordPress, the "theme" is what holds the payout and design of the page. From this last explanation, it sounds like you're using the word "theme" to mean a section of the side that paid users can have access to - the layout and design isn't really what matters.
If I'm wrong, please correct me on that. However, assuming I'm right...
I'm not sure how you plan to pass out the course information, but in WordPress, you *can* password protect posts and Pages. So, for example, you could create a Page (or post - but in this case, I think a static Page would be better) for each months' "education" and password protect it. When someone comes through with the payment for month 1, you send them the password to that Page so they can obtain their education. Month 2, the same way.
Does that make sense to you? Hopefully that's what you're looking for. :)