B2C Scenario with Fiori - consumer user license

Hi Colleagues,

Our customer desires to develop a new website for B2C scenario; there will be more than 30 thousand consumers accessing the website for creating consumer data and registering new sales orders.

The consumer needs to do a logon into the website before proceed with the sales order creation, similar to a WebShop.

We are considering the usage of SAP Fiori integrated with SAP Gateway, using oData services to traffic information with the backend systems (ECC,CRM).

However, we want to know how SAP works with user license cost for the mentioned scenario above? Can someone detail us how it works?

Thanks in advance.