What does OEM mean?
OEM product keys are priced lower than their retail counterparts,
but use the same software as retail versions of Windows. Per
Microsoft's EULA regarding OEM, the product key is tied to the PC
motherboard which it’s initially installed on, and there is
typically no transferring the key between PCs afterwards.
Can I directly upgrade from an older operating system?
No, you cannot. A clean installation is required.
What is a clean installation?
A clean installation means formatting your hard drive before
installing Windows, so make sure that you have backed up your
files.