This article assumes you have already assigned the Windows 10 Enterprise license to your customer.
1) Log in to the Microsoft Partner Center
2) Open the Dashboard
3) Select Customers from the left-side menu
4) Under the ‘Customers’ select a customer
5) Select ‘License Management’ from the left-side menu and assign a Windows 10 Enterprise license to a selected user
Repeat these steps for all users appointed by the customer to receive the Windows 10 Enterprise upgrade on their devices.