This allows members to create a login to the webpage and pay for their membership through there with PayPal (either manually each period or with a subscription). For those managing the space the admin logins allow managing membership types, prices, duration, etc as well as assigning RFID cards/fobs to peoples accounts.
The typical way this works is that you create a nodes for the doors of your space and set access to them based on a specific membership type and time or just having any valid membership. When a person has paid (in cash and manually entered by an admin or via paypal themselves) for a membership the system keeps track of your status with a database and only lets people in if they've actually paid. You can also just give people or groups of people access (possibly with time/date constraints) or just make the door be unlocked automatically during "open" hours or for events.
I want to expand the system to include mobile apps (basically a better interface for the site on phones, either mobile friendly web-app or native apps) and better accounting integration. It would be great if payments could be through multiple different providers (based on what you might want to use) as well as integrate into Quickbook or other accounting software to keep the accounting of member management simplified. Finally making nodes capable of integrating and doing more things like working with vending machines, or controlling access to machines as well as doors.
Ah, the hackspace membership system. The holy grail :)