Thanks for your great questions
Do you provide Authorize.net and/or Stripe for RECURRING credit-card processing?
s2Member® Pro does provide integration with PayPal®, PayPal® Pro, Authorize.Net®, ClickBank®, and Google® Checkout. These all integrations all support recurring billing. s2Member® Pro does not, however, support Stripe. There are plans for integration with Stripe in the future, but we do not have a set time frame for when this integration will be released.
Check Pre Sale FAQs » What payment gateways does s2Member® support? for more info on this.
And if a user does not cancel but his card no longer works with, say, Authorize, what happens? He gets a notice (from whom?) with a grace period before being cancelled (automatically, I hope)?
Authorize.net’s processes would notify the user that the payment failed. s2Member gives a 24-hour grace period to a user’s End of Term (the date that the user will be demoted/deleted) when a user pays for subscription. If the user does not modify his billing profile via Billing Modification Forms, they will be demoted/deleted depending on what you have set up under Dashboard -› s2Member® -› Authorize.Net® Options -› Automatic EOT Behavior.
When testing this functionality with Authorize.net, you may notice that when you refund a user, or stop a subscription, that the user is not demoted. This is to be expected, as Authorize.net does not send info to s2Member when a user stops subscription. Instead, Authorize.net’s processes set up an End of Term on every payment, and if this End of Term is not extended by receiving payment in the future, s2Member will demote the user.
This is outlined under Dashboard -› s2Member® -› Authorize.Net® Options -› Automatic EOT Behavior, which is available when you have installed s2Member® Pro.
The above is NOT true for other payment gateways, such as PayPal®, and PayPal® Pro.