This seems to depend on whether you are using a retail or volume license. As it is not clear from the question, I am going to cover both.
Microsoft have published an official guide (Licensing Windows desktop operating system for use with virtual machines) that suggests with Windows Software Assurance or Windows VDA Licensing you can run up to 4 copies of a licensed Windows desktop image concurrently in virtual machines.
The PDF brief postulates the following scenario:
An organization has a group of developers who need to test an
application across multiple Windows images running in local virtual
machine on PCs running Windows 10 Pro.
Licensing Solution:
The PC or the primary user of the PC needs active Windows Software
Assurance, which permits running up to four virtual machines
concurrently.
So in summary, if you have Windows Software Assurace / VDA then it appears that yes, you can run a single Windows license as a host and guest on the same machine.
However, if you are using the retail copy of Windows (without a Software Assurance or VDA addons) then I will refer you to @sahsanu's answer, which appears to be no.
I would strongly advise checking the terms of use that came with your Windows 10 license in either case.
2There are exceptions, see @plasmid87 answer! – Barry Staes – 2016-05-03T09:00:21.257