Since Windows 10 (or earlier?). It has become standard to store the license product key in the UEFI/BIOS.

I am in the market for buying a new (custom build, individual parts) PC with a new Windows 10 License.

However I was wondering (and can't find clear information on this subject). What the differences between the licenses are when it comes to OEM and Retail.

If in the far future I were to sell this PC:

  1. Would the license (whether OEM or Retail), be stored in the UEFI/BIOS, where it could be used by the new owner?
  2. If so, can I remove the license key from the UEFI/BIOS?

I want to know this because I don't want to buy Windows 10 every single time I buy a new PC (since no new versions of Windows will be created, only updates).

  • It's not stored in the UEFI it's stored in the ACPI table which the UEFI shell can access. They are not the same thing. If you build your own machine, the license key must be a retail license, it's not possible to get an OEM license on a custom built PC. The ACPI has a specification for how the Microsoft Windows key is stored, which is only applicable, to actual OEMs not you the end user – Ramhound Aug 3 '16 at 8:02
  • @Ramhound Is this ACPI storage located on the motherboard or on the SSD/HDD? and can I remove licenses from this storage, so that they can be reused on new systems? – JSmith Aug 3 '16 at 8:04
  • Doesn't matter your building a custom PC, your ACPI table won't contain a Microsoft license, you as the end user can only purchase retail copies of Windows 10. Your system drive has NOTHING to do with the ACPI table – Ramhound Aug 3 '16 at 8:05
  • @Ramhound they do sell OEM licenses in the stores in my country too. – JSmith Aug 3 '16 at 8:12
  • If you are buying them then they are a retail OEM license, they are still, a paper license (I.e you get a key) – Ramhound Aug 3 '16 at 9:17

Windows doesn’t embed the key, the OEM has to do that. I guess a built-to-order PC won’t have a key embedded. It’s unlikely a hardware shop has the tools required to do it.

Simply put: If there isn’t a key now, there still won’t be one after installing whatever Windows version you procure.

As for the second question: You can’t remove it. The ACPI tables (location of key) are provided within the (UEFI) firmware which you cannot update yourself.

  • So if I assemble and install the PC myself the license won't be stored on the PC (UEFI/BIOS)? – JSmith Aug 3 '16 at 8:06
  • 1
    That’s correct. – Daniel B Aug 3 '16 at 8:06
  • In my country they sell OEM licenses in the stores, can these be reused with new hardware (custom builds)? – JSmith Aug 3 '16 at 8:28
  • 1
    Yes: “Can be transferred to new hardware, if removed from the prior PC.” Just ignore the rest of the terms, you’ll just get a stomachache. Microsoft won’t ask and you won’t tell. – Daniel B Aug 3 '16 at 8:46

OEM licences live and die on the machine that they were installed on by the manufacturer. If you were to sell the machine then the licence goes with it.

Retail licences are yours. You can uninstall (format) the machine it was on and move it to another machine.

To clarify though, OEM licences were stored in UEFI/BIOS, but now you have "digital entitlement" where your licence is stored online with Microsoft along with a hash of the details of the machine hardware.

  • 2
    Windows 10 licenses are still stored in the ACPI table. Digital entitlement licenses only apply in specific cases. A retail license of Windows 10 can be moved to other machines, same as always, an OEM license cannot. A digital license depending on specific factors can be moved but not without a call to Microsoft, and only if, the original license was a retail license – Ramhound Aug 3 '16 at 8:07
  • I hear some rumors that a personal license can be used on several machines? For example your desktop and your laptop, but I never checked. Any idea? – Stein Åsmul Jun 27 '18 at 19:55
  • @SteinÅsmul I've seen allowances like that for Microsoft Office, but not Windows. – Mokubai Jun 28 '18 at 4:07
  • What about virtual machines created on a Windows 10 Pro box? I haven't tried this so far. – Stein Åsmul Jun 28 '18 at 13:30
  • @SteinÅsmul for Windows 7 and 8 it was always on the host hardware or virtual machine, but not both at the same time. All "machines" had to have a valid licence, whether it was transferred from host to guest or otherwise: superuser.com/questions/25678/… I'd have to look into it for Windows 10 but I doubt it has changed. – Mokubai Jun 28 '18 at 14:30

An OEM / System Builder License can be purchased but you cannot write the product key to the UEFI. The biggest difference is the support you would receive.


I have an oem license from Microsoft. Not the oem end-user but an OEM hardware manufacturers license. This is what I did.

Right click the desktop and go through your settings and set your computer as a developer.
You will need an IDE. Visual Studio Community is free. Download and install the Software development Kit (SDK) and the Windows Assessment and Deployment Kit (ADK).

You are a Computer manufacturer and your company name is [whatever] mine was Used-Parts Custom Computers and Tailor Made Winstallations.

The process of making (or learning about making or deploying) a branded Custom Windows for your own Company that makes a hardware device requires you to be an OEM. This is the workaround as recommended by Microsoft in their ADK tutorial Creating a Custom Windows for Deployment tutorial at msdn (i think). Whether it's limited in duration or scope, or or not, doesn't matter. You now have an OEM license that passes the Microsoft screening.

As to whether you can access the table to alter or edit the Product key? I just found out about the product key in the eufi, we'll have to wait and see. I will follow up. The key is injected at the mfg not in Redmond so I'm thinking the mfg gets a tool. I will ask for one. But the oem should be based on GUID. if you add, remove, or replace any hardware device that is in the GUID, the computer will get a new GUId. This probably only applies to people who want to escape their OEM product key. I think the sound card, graphics card and network card and processor make up the guid. Just change one of them for a new number and you should be able to escape out of the OEM label.

If you want to "add" to the uefi to escape having to put in the key every time you install Windows, just make a system image of your windows and designate a hdd as a Backup location. Make the image after all the updates, drivers, and software have been installed. Making a second one at a network location is a good idea also. This will automate the entire installation. A send option is You can edit the wim file and stream in your product key. I think the file name is install.wim? not sure. I've heard of it but never tried. Third option is to make a deployment using an answer file. Basically the installation refers to a file that you prepare that holds all the information the Windows install needs. You can include other stuff as part of the install. The answer key is where you add the product key.

  • A wall of text is not helpful as It's hard to understand for others. Your answer needs to be edited , limited and formatted. – C0deDaedalus May 26 '18 at 14:57
  • ty....but I've never posted a question here that was actually answered and it's not surprising that I get a response when I didn't even ask a question. Do you make corrections in red ink as well? – S1Niz7el2 Jun 19 '18 at 10:24

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