Will I get a product key, can I get a product key?
By default, Windows 10 builds are pre-keyed, meaning, you do not have to enter a product key and should not be prompted to enter one even after Windows 10 has completed setup.
Microsoft tells me that it will be possible to do so. And that a key part of this process is that it will save a product key tied to the previously upgraded PC or device in Windows Store. This is how Windows 10 will later know that the install is allowed: It’s “one of the benefits of the new delivery system,” a Microsoft representative told me.
Windows Insider MVP
MVP-Windows and Devices for IT