Are cheap Windows keys legit? Retail vs OEM vs Volume keys explained
Not every cheap key is a bad key, and not every key is what the seller says. Here's how Windows and Office licensing actually works, so you can tell the difference.
Updated 7 October 202601Why keys cost less than in the Microsoft Store
Microsoft's own store sells at full list price. Independent resellers set their own prices, like any shop, and digital keys have no packaging, shipping or shelf costs. That's why a genuine key can cost far less than the Microsoft Store price.
A low price on its own doesn't make a key fake. What matters is what type of key you get and whether the seller stands behind it.
02The three types of keys
| Retail | OEM | Volume (MAK / KMS) | |
|---|---|---|---|
| Meant for | Anyone | PC makers, preinstalled | Companies and schools |
| Move to a new PC | Yes | No, tied to the first PC | No |
| Activation | Online, once | Online, once | Shared key or company server |
| Risk when resold | Low | Medium | High: can be blocked later |
Retail keys
The same kind of key Microsoft sells in its own store. It activates online and stays activated. If you replace your PC, you can move the license to the new one (one PC at a time). All keys sold by SOS License are retail keys.
OEM keys
Made for PC manufacturers and system builders, who install Windows on new computers. An OEM license is locked to the first PC it activates. It works, but if you change the motherboard or buy a new PC, you need a new key.
Volume keys (MAK and KMS)
Volume licenses are sold to organizations. A MAK key can activate a set number of PCs, and Microsoft can block it once it's been shared too widely, so a PC that worked for months can suddenly show "Windows isn't activated". KMS activation needs a company server; "KMS activator" downloads are piracy tools and a common way to get malware. Avoid both as a home user.
03Red flags when buying a key
- Unrealistically low prices: a few dollars for Windows or Office usually means a shared Volume key.
- Phone activation only, or instructions to run a script, a "loader" or an "activator".
- A shared Microsoft account instead of a key, or a "lifetime" Microsoft 365 subscription for a one-time price.
- No refund policy, no support contact, or a seller you can't reach after paying.
- Payment by gift card, crypto or bank transfer only, with no buyer protection.
04What to look for instead
- Online activation through Microsoft, with no extra tools.
- A written guarantee that you get a working key or your money back.
- A payment method with buyer protection, such as PayPal or a credit card.
- Real support you can contact by email or chat.
At SOS License every order is paid through PayPal, activates online, and is covered by our 30-day guarantee: if your key doesn't work and we can't fix it, you get your money back.
05Is buying a key from a reseller legal?
In the European Union, the Court of Justice ruled in 2012 (UsedSoft v Oracle) that software licenses can be resold. Rules differ between countries, and this guide isn't legal advice. In practice, what protects you as a buyer is a genuine key that activates online, a seller that guarantees it, and a payment method you can dispute.
06How to check your key after activating
Open Command Prompt and run slmgr /dlv. The Description line shows the channel, for example RETAIL, OEM or VOLUME_MAK. See how to check if Windows is activated for more.
