Dear Steven,
Thank you for using our EShop Shopping Cart extension and submitting the ticket here. Regarding your question: I think you can also use our Membership Pro extension to manage classes as plans. Then we have an integration feature between EShop and Membership Pro: When a customer purchases a product in EShop, then he will be subscribed to a specific plan (which is assigned to product in the setting).
I think it should work as you want.
Sincerely, Giang