Hello! I am not talking about Windows PE for installing over the network.
I am talking about running Windows on a bare metal diskless client from a NAS share.
Is it possible? Does it require further costs and licensing? Are there any other alternatives?
You could look into iscsi boot. This sounds like what you are talking about.
https://docs.microsoft.com/en-us/windows-server/storage/iscsi/iscsi-target-server
There is a recent thread with a how to here- Rages disk-less Windows 10 boot from iscsi - Adventures / Results
A few of us are actually working on that. You need iscsi on your server.
Also @Ragebone is as well. It can be done with linux or MS Server 2012+ Microsoft can be setup with iscsi luns backed by VHD images with snapshot capability. And Linux can be configured to use … just about anything you can block level mount for iscsi luns. I’ve experimented with using linux imaging solution for reimaging regular home pcs. I’ve found nothing more convenient than pxe booting a customer pc to live debian, and pulling down an image from NFS. Nothing beats the transfer speed… YMMV
If you want to boot baremetal PCs from a free solution you need ipxe, tgt, dnsmasq (or highly option custimized dhcp server),(memdisk or wimboot for the install) a customized winpe with your network drivers injected. And a couple weekends of free time. Review the links and hit us up with questions, it’s a pretty friendly forum.
@moriarty is correct 
Though, you can reduce the needed software stack to:
dnsmasq, ipxe, iscsiTarget, windows (bootable and or installer).
It is in general rather easy, but if you get problems, oh boy. Good luck!
System Upgrades will very likely self destruct. Actually a Bug so #Fuck M$
And the performance over iscsi sucks!
i will have to look into the NFS VMware image thingimagic.