For recurring Stripe subscriptions, how does a customer update an expired/replaced credit card or manage their subscription?

I see that WPSmartPay has a customer dashboard with a Subscriptions area, and the Pro plugin appears to include Stripe Billing Portal functionality for managing payment methods and subscriptions. However, I don't see how a customer actually launches the Stripe Billing Portal from the SmartPay customer dashboard.

I don't want my site collecting or managing card details. Ideally, a customer would click something like Manage Billing or Update Payment Method and be securely sent to Stripe's hosted portal.

Is this currently supported in the customer-facing UI? If so, where is the link/button enabled? If not, what is the intended process for a customer whose card expires or needs to be replaced?