Build an Online Store

Hi, I have an existing website that I want membership level enhancements. I want to sell different membership levels and control what pages the member can access once they log into my site. When buying a membership level package I can set cost and details about that membership level. Once the member select the membership level they want it will redirect them to pay for membership like using Paypal. They can also register for a free membership level as well in this case they will just register without being directed to secure pages based on that membership without any payment option. As the admin of my website I should always have full access to all pages using my admin subscription login. The member can also recover forgot passwords and I have full access to manage all my members subscriptions and notify the member that their membership will expire the member can also select to auto renew their membership level. Whatever you use to create my requirements listed above must be a free solution without any future occurring cost to maintain this login functionally and must be fully documented so I can support this custom login if anything stop working with this tool or my website. My website is built in WordPress. I must also have to ability to update members role on the backend and what pages can be accessed based on their membership level at anytime. Also, remove the custom login I currently have setup on my website now. It should also have to ability to manage downloadable documents and software See link below I want something like this but a custom built free solution [login to view URL] Thanks