Members Subscription via Paypal

I currently have a domin that has a free section and a members section. To become a member people have to register, pay a subscription fee (via paypal) and then once payment has been accepted via paypal the system emails the a password. They then can log in and out of membersarea.

Is there a plug-in/facility for wordpress to have a paid subscription system?

Ive emailed the creator of the system I currently use to see if it can be adapted to WP, has anyone else got this system?