Paypal Subscription Button is a WordPress plugin by adred that integrates a Paypal subscription button into WordPress.
WordPress Paypal Subscription Button Admin
Features:
Supports multiple membership levels
Supports sanbox/testing mode
Intuitive and clean backend for configuration
Allows sending all IPNs to your email address to monitor every transaction
Supports hosted/not-hosted button
Download and info: http://wordpress.org/extend/plugins/paypal-subscription-button/