Integrate with WooCommerce Subscriptions

Hey guys, just checking https://senseilms.com/documentation/selling-courses-as-a-subscription/ which seems to work fine. What I was wondering is if it possible for us to attach a subscription to existing customers that already purchased a product?

For example, we have a course/product (which was set as a simple product) with a set fee for checkout. We already have members/students enrolled. Now we installed the WooCommerce Subscriptions plugin as we want to add a recurring fee each month, so we edited that product from simple product to simple subscription, which seems to apply for subsequent customers that purchase that course/product, am I right? So how do we go about adding that monthly fee/subscription to the students that have purchased the product/course before?