The install-only keys (for bypassing the key step), stopped working. The normal materials in this case, is to make a Rufus boot USB, and first try adjusting/adding the EI.cfg file which pretends to be a VLK Professional. I don't think the PID.txt file would be worth adding, as I suspect that key is one of the blocked ones.
Windows 8.1 Pro (make a VLK from USB key, no "key" prompt)
EI.cfg
[EditionID] Professional [Channel] Retail [VL] 0PID.txt
[PID] Value=XHQ8N-C3MCJ-RQXB6-WCHYG-C9WKBThere were six or more keys similar to that previous value. Three of them for W8.0, three for W8.1. They would only give you the 30 day grace period, and bypass the need to insert a "real" key immediately. That's why they are called install-only keys, as their only purpose is to get past the key entry thing, then on day 29, you use the key-change feature to change to another license key, and then your OS can be officially activated.
XKY4K-2NRWR-8F6P2-448RF-CRYQH (Windows 8 Professional) RR3BN-3YY9P-9D7FC-7J4YF-QGJXW (Windows 8 Professional with Media Center) FB4WR-32NVD-4RW79-XQFWH-CYQG3 (Windows 8 [Home]) XHQ8N-C3MCJ-RQXB6-WCHYG-C9WKB (Windows 8.1 Professional) GBFNG-2X3TC-8R27F-RMKYB-JK7QT (Windows 8.1 Professional with Media Center)
334NH-RXG76-64THK-C7CKG-D3VPT (Windows 8.1 [Home])But those are the materials, and it's possible just using the EI.cfg file is sufficient at this point in time. If the value in that PID is blocked, I can't see offering it is going to help matters exactly.
I like the ability, to not "burn" a System Builder license key, until I'm completely satisfied the rig has the right drivers and so on.
Paul