Windows 10 Product Key: Where to Find Yours and How to Buy a Genuine One (2026)

Reviewed 6 October 2026 by Justine, Technical Support Advisor at Nerdused. Nerdused prices checked on the same date.

A Windows 10 product key is the 25-character code (XXXXX-XXXXX-XXXXX-XXXXX-XXXXX) that activates Windows 10. If your PC is already activated, you usually do not need it: Windows 10 reactivates on its own when you reinstall it on that PC. If you need a new one, a genuine Windows 10 Pro key costs $24.99 at Nerdused. Microsoft ended free support for Windows 10 on 14 October 2025, so before you buy, check whether your PC can run Windows 11 instead.

Windows 10 product key at a glance

What it is	A 25-character code used to activate Windows
Where you enter it	Start > Settings > Update & Security > Activation > Change product key
When there is no key to find	Free upgrades from Windows 7 or 8.1 and Microsoft Store app purchases use a digital licence instead
Edition	The key must match the edition installed, Home or Pro
Windows 10 support	Ended 14 October 2025. Consumer Extended Security Updates run until 12 October 2027
Nerdused price	Windows 10 Pro key: $24.99 for 1 PC, $29.99 for 3 PCs, $49.99 for 5 PCs
Licence	For the PC it activates on. Reinstalling Windows on that PC is fine

What is a Windows 10 product key?

Microsoft defines a Windows product key as a 25-character code used to activate Windows. Activation is Microsoft's online check that the key is valid and not in use on more devices than its licence terms allow. A PC can also activate with a digital licence and no key, which is why a PC that was already activated can reinstall Windows 10 without one.

Where to find your Windows 10 product key

Where the key is depends on how the PC got Windows 10. This is Microsoft's own list:

How you got Windows 10	Where the product key is
Preinstalled on a new PC	Preinstalled on the PC, in the packaging, or on the Certificate of Authenticity (COA) attached to the PC
Boxed copy from an authorised retailer	On a label or card inside the box
Digital copy from a retailer	In the confirmation email, or in a digital locker on the retailer's website
Free upgrade from Windows 7 or Windows 8.1	No key. The PC has a digital licence
Bought in the Microsoft Store app	No key. The PC has a digital licence

A key bought from Nerdused is in your order email, and our support team can resend it. If the key is stored in the PC's firmware, one command reads it back: see how to find your Windows product key.

Do you still need a Windows 10 product key in 2026?

It depends on the PC. Windows 10 still runs, but since 14 October 2025 it no longer gets free security fixes.

• The PC meets the Windows 11 requirements (a compatible 64-bit processor, 4 GB RAM, 64 GB storage, TPM 2.0, UEFI with Secure Boot). Move to Windows 11. The free upgrade activates with a digital licence, so an activated PC needs no new key. Our Windows 11 upgrade guide has the steps.
• The PC does not meet them. Windows 10 is the practical choice, and it needs a Windows 10 product key if it is not activated. Enrol it in Microsoft's consumer Extended Security Updates (ESU) programme too. Microsoft says you can enrol until the programme ends on 12 October 2027: at no extra cost if you sync your PC settings, for 1,000 Microsoft Rewards points, or for a one-time $30. ESU adds security updates; it does not activate Windows.

How to buy a genuine Windows 10 product key

Microsoft's own store no longer helps: when we checked on 6 October 2026, its old Windows 10 Pro page showed Windows 11. That leaves resellers, so run five checks before a Windows 10 product key purchase.

1. A named, accountable seller. Nerdused Ltd is a UK company (no. 16876657) and a member of the Microsoft Partner Program (ID 6467441).
2. The right edition. A Windows 10 Home key will not activate Windows 10 Pro. Check your edition under Settings > System > About.
3. Activation inside Windows. A genuine key is typed into Settings and activates with Microsoft. Avoid any seller whose instructions involve an activator tool or a script.
4. A clear PC count. Ours cover 1, 3 or 5 PCs, and each licence is for the PC it activates on.
5. A written refund policy. Ours is a 30-day refund promise if the key has not been used or will not activate.

Microsoft says error 0xC004C008 can appear when the key has already been used on another device, or on more devices than the licence terms allow. If activation is blocked with error 0xC004C003 instead, see our guide to fixing error 0xC004C003. OEM vs retail Windows keys explains the licence types.

What a Windows 10 licence costs in 2026

Option	Price	Good to know
Windows 10 Pro key, Nerdused	$24.99 for 1 PC, $29.99 for 3, $49.99 for 5	Also activates Windows 11 Pro
Windows 10 Home key, Nerdused	$24.99 for 1 PC	The listing explains an extra VPN step during installation. Read it before you buy
Windows 11 Pro key, Nerdused	$29.99 for 1 PC	For PCs that meet the Windows 11 requirements
Windows 11 Home or Pro, Microsoft Store	$139.99 or $199.99	Microsoft's store now sells Windows 11

Every Windows key we sell is on the Windows licence keys page.

How to activate Windows 10 with a product key

1. Select Start > Settings > Update & Security > Activation. Shortcut: press Windows + R, type ms-settings:activation and select OK.
2. Select Change product key.
3. Enter the 25-character Windows 10 product key and follow the on-screen instructions.
4. Stay online while Windows checks the key with Microsoft. The Activation page then shows that Windows is activated.

On a clean install, Windows Setup asks for the key and you can enter it there instead. Entering a Pro key on Windows 10 Home upgrades the PC to Pro in place.

FAQs

Can you still buy a Windows 10 product key in 2026?

Yes. Resellers including Nerdused still sell genuine Windows 10 Pro and Home keys, although Microsoft's own store has moved on to Windows 11.

How much does a Windows 10 product key cost?

At Nerdused, a Windows 10 Pro key is $24.99 for 1 PC, $29.99 for 3 PCs and $49.99 for 5 PCs. A Windows 10 Home key is $24.99 for 1 PC.

Does a Windows 10 product key still work after end of support?

Yes. End of support stopped free security updates, not activation. The Windows 10 keys we sell activate online with Microsoft today, and the 30-day refund promise applies if one does not.

Can I use a Windows 10 product key for Windows 11?

The Windows 10 Pro key we sell also activates Windows 11 Pro. An already activated Windows 10 PC that takes the free upgrade needs no key at all: Windows 11 activates with a digital licence.

Will my Windows 10 product key work after I reinstall Windows?

On the same PC, yes. The licence is for the PC it activated on, so reinstalling the same edition there is fine, usually without typing the key again.

Sources checked 6 October 2026: Microsoft Support, Find your Windows product key, Activate Windows and Get help with Windows activation errors; Microsoft, Windows 10 Extended Security Updates and Download Windows 10; Microsoft Learn, Windows edition upgrade.