incremental content question

Hi,

I would liket to understand the incremental plugin.

I usually install my site this way:

1 wordpress installed at the root of my domain (ex: www.mysite.com)
amember for protection (ex: www.mysite.com/member)
1 wordpress inside the member area (ex: www.mysite.com/member)

I prefer to install 2 wp because it allows me more flexibility with navigation, etc.

So, if I need to create a subscription (example 50$ per month), and then when people pay, they receive access to the member area and the content for the first month. On their second payment, they receive the content of month 2 and still have access to month one.

Will this work with a double wp installation?

If so, do I install a plugin only in the wp that is installed inside the member area?

Thanks in advance for your help!