Hi Kate,
You only need PayPal Pro if you want to accept payments on-site with s2Member Pro. You can certainly use s2Member Pro without a PayPal Pro account:
*PayPal® Pro is NOT Absolutely Required* s2Member is very flexible. It is now possible to integrate Pro Forms without a PayPal® Pro account, whereby the enhanced Form Shortcodes that s2Member provides can be integrated ONLY with PayPal® Express Checkout. In other words, if you get declined for PayPal® Pro service, you can still use s2Member Pro Forms. Ask PayPal® to activate Express Checkout for you. ( it’s free ). Once Express Checkout is enabled, you will have access to your PayPal® API Credentials. Log into your PayPal® account, and navigate to Profile -> API Access (or Request API Credentials). You’ll choose ( Request API Signature ). Now … here is the tricky part; whenever you generate a Pro Form Shortcode with s2Member, be sure to change accept=”paypal,visa,mastercard,amex,discover,maestro,solo” to just accept=”paypal”; thereby excluding the on-site credit card processing functionality; which is available only with PayPal® Pro.
You can definitely accept recurring subscriptions with a PayPal Basic Business Account, however you may need to have PayPal enable recurring subscriptions on your account (it’s free). I suggest checking with them to confirm that you account has that feature enabled.
For more information on PayPal services, see Video » By PayPal®, Service Introductions (Highly Recommended).