Rapidweaver Membership Site

I have developed a site in Rapidweaver. I want the site to have paid limited membership access. Members will be given 6 months access to the site for a fee. I would need access to the site to be limited to Username/Password and allow for only one member at time to use that Username/PAssword and a limited number of places a Username/Password could connect from. The site replaces a text for a course and I want to limit Username/Password as much as possible. I use a Paypal business accont rightnow for sale of the paperback text. I do not have any skills for this. I know there are a number of relatively inexpensive products out there to do this but don't know the best one to use or how to use it.