Federated Core Platform includes a service allowing your customers to navigate to an information website to learn about Federated Core services and offerings, sign up for a management account, then procure/modify/cancel Core subscriptions.

The billing engine is the accounting engine that tallies all the various product offerings delivered to a customers. It is not a payment platform but works with your payment platform of choice including Stripe, Auth.net, various crypto services, or something built in-house.