It is, when you activate "free site" you have to uncheck all the boxes in "access to areas"
Once you activate one of the areas, the members have to pay for it.
The way I do it, Free site is also marked "on" but I already made the "access to areas" for the future, some boxes are checked, others are unchecked.
For the moment my site is stil free but I give every new member 120 days full memberschip manually.
How to do it?
Users>edit
Then change the "type" to platinum
"Gold days left :" You put the number of days the member get full access.
Be sure that all the boxes are checked for platinum in the "access for areas".
I see two advantages this way,
1. I have good control of who becomes a member by checking them manually
2. I'm sure that every new member has full access to the site
Hope this helps