Windows 11, Windows 10, Pro or Home license, at the client’s choice + installation at home or sending/bringing the computer to my office.
No, never. You will only make the payment when your Windows is registered with its official license and installed on your computer.
These are completely official and valid Windows licenses and you’ll verify by yourself.
There are many companies with surplus Microsoft licenses, and businesses that cease their operations and dispose of unused, bulk-purchased Windows licenses. I purchase licenses from those kinds of companies.
I’ll use another valid license, and obviously, there won’t be any kind of surcharge for you. You don’t pay for the service until your Windows is registered and installed on your computer.