Properly Licensing Windows: Edition, License Type, Migration

A Windows license is valid for exactly one computer. There is no user license and no household license. Three computers mean three licenses, even if only one person is working on them.

This is where Windows and Microsoft 365 are regularly confused. With Microsoft 365, the license is tied to the account and covers multiple devices. With Windows, it's tied to the hardware. Those who mix the two up in their minds will be under-licensed.

The same rule applies to virtual machines: every running Windows instance needs its own license. The test system in VirtualBox or Hyper-V is no exception, even if it runs on the same computer.

OEM, Retail, and Volume Licenses are functionally identical. They differ in only one aspect, which usually only becomes relevant when changing hardware:

• OEM: tied to the motherboard upon first activation. If the board dies, the license dies. Replacement due to defect is the only recognized exception.
• Retail: transferable. You may remove it from the old computer and activate it on a new one, but only sequentially, never in parallel.
• Volume License: comes from a company's framework agreement. This is the type that is traded on the used market because it can be cleanly detached from the previous owner.

You don't have to guess what type of license your current computer has. Open the command prompt and type slmgr /dli. The window will display the activation channel, i.e., RETAIL, OEM_DM, or VOLUME_MAK. Then you'll know if it's worth moving to new hardware or if you need a new license.

Regular support ended on October 14, 2025. Computers still boot, programs still run, but monthly security updates are missing. That's precisely the problem, because every newly discovered vulnerability remains permanently open.

Three paths are open, and the order of examination is crucial:

• Hardware meets requirements: Upgrade to Windows 11, free of charge, the existing activation is transferred. Requirements are TPM 2.0, UEFI with Secure Boot, and a processor from Intel 8th generation or AMD Zen+.
• Hardware does not meet them, but should remain: ESU extends updates for a fee. The first year for private users ends in October 2026.
• New hardware without license: here you need your own Windows 11 license, because an OEM license does not transfer.

Whether your computer meets the requirements can be shown by Microsoft's PC Health Check. For a quick preliminary check, tpm.msc is sufficient: If it shows a specification version 2.0, the biggest hurdle has already been overcome.

You handle everything important for activation in the command prompt as an administrator. These four commands cover practically every case:

• slmgr /dli shows the license type, activation channel, and the last five digits of the installed key.
• slmgr /xpr answers whether the activation is permanent or has an expiration date.
• changepk.exe opens the dialog to change the product key without reinstallation. This way, Home becomes Pro without data loss.
• slmgr /upk followed by slmgr /cpky removes the key from the computer and deletes it from the registry. You take this step before giving away a computer.

If online activation fails, the telephone method via slui 4 remains. This also works even if the activation server initially rejects a key after a hardware change.

The resale of used software is permissible in the EU; the European Court of Justice ruled this in 2012 in case C-128/11. However, what is traded for a few euros on marketplaces usually does not fall under this ruling.

Typically, these keys come from one of three sources:

• maxed-out MAK keys from third-party volume license agreements, whose activation quota is eventually exhausted,
• OEM keys from scrapped hardware that were never individually transferable,
• keys from regions with lower price levels that are not valid outside their market.

The damage rarely becomes apparent immediately. The computer activates, runs for weeks, and then reports itself as not activated as soon as Microsoft blocks the key. Without an invoice and without a chain of proof, you are left with nothing.

Therefore, you should demand three things with every used purchase: an invoice with VAT shown, proof of the original license, and written confirmation that the previous owner has deleted their copy.