WP Pro Members
WP Pro Members is a feature packed WordPress Membership Management Plugin allowing anyone to turn a WordPress Blog into a fully functioning members site which can accept payments through Paypal, ClickBank and WorldPay.
It supports multiple membership levels like Silver, Gold or Platinum.
Each membership level can have unlimited subscriptions. You can charge monthly while offering a discount for annual subscriptions. You can force specific payment terms for individual membership levels, you may want one membership level to only be available to annually paying members. Each subscription can vary anywhere from 1 day to 24 years, you decide the exact recurring length of individual subscriptions allowing complete control.
You can even have a Pay Per Post option which allow user to pay for a single post on your blog.
Why a membership site
Membership sites have been proven to be one of the most effective methods of generating serious, residual income online. They also require the least amount of work to get started. With the combination of minimal start-up effort and maximum profitability, it is no wonder why membership sites have become such a profitable business model.
Over the years, WordPress has emerged to be the absolute best platform for membership sites. They are easily the most flexible and easy to use content management systems on the internet. The best part is that it created by an open source community, which means it is completely free to use.
The entire process of setting up a membership site with wordpress can be completed with an hour or two. All you need to do is install WordPress, which can be completed in a matter of seconds. Next, you choose a theme that will control the layout of your membership site. Finally, you install a series of plugins to optimize your SEO, control your membership and administration, create a forum, chat rooms, videos, as well as control any additional features that you may need to add to your site.
Anyway, the plugin can be found on WP Pro Members official page