Hello,
1. can customers cancel their subscriptions from within wordpress?
Yes. Please see Dashboard -› s2Member® -› PayPal® Buttons -› Subscr. Cancellation Buttons in the free version of the plugin and Dashboard -› s2Member® -› PayPal® Pro Forms -› Billing Cancellation Forms in the Pro version (the cancellation form is also available for Authorize.net). These forms/buttons can be placed within WordPress and displayed to the user on a cancellation page, allowing the user to cancel their subscription.
3. do you happen to have a way for each logged-in customer to view a license key that is unique to them?
Yes, you can use Custom Registration Fields for this (Dashboard -› s2Member® -› General Options -› Registration/Profile Fields). You can create a field called “License Key” and then display that field to the user after he logs in. You’ll need to take care of generating the licence key and adding it to the Custom Registration Field.
4. does your solution allow multiple payment methods to be active at once, so the user can choose from paypal or authorize.net?
Yes, you can have multiple payment gateways configured and active and present these as options to the user before checkout. You’ll need to ask the user beforehand which gateway he wants to use and then send him to the correct checkout page.