Windows 10 is available in two versions: The Home and the Pro version. Within this version you can opt for a Retail or OEM license.
The difference between a Retail and an OEM license is that an OEM license can only be installed on new computers (new hardware).
This OEM license may be used for installation once and afterward it is bound to the hardware of that computer.
Do you want to be able to transfer the license when you buy a new computer? Then choose for a Windows 10 Retail version.