Are Windows 10 keys that are sold for 4 euros on eBay legal?

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There are numerous licenses and keys for Windows 10 Home and Windows 10 Pro that are sold every day through pages such as Amazon or eBay for the ridiculous amount of 4 euros and up to 3 in some cases. As of today, the official price of a Windows 10 Home and Windows 10 Pro license starts at 145 and 259 euros respectively. The doubt about their authenticity and the origin of these licenses remains in the air. Are they pirates? Do they have an expiration period? Why are they so cheap? We see it below.

Cheap Windows 10 keys: equal parts legal and illegal

Windows 10 keys that are sold for 9, 4 and even 3 euros. Pages like eBay and even Amazon clutter their virtual shelves with these types of keys. But are they as legal as they seem?

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The truth is that yes. Like the rest of the keys, these are distributed by Microsoft itself, so they are fully valid to activate the corresponding Windows 10 version . The crux  of the matter, and the reason for the low price of these types of licenses, is because they are OEM keys. One of the main characteristics of OEM keys is precisely that they cannot be distributed to third parties , much less sold to end users.

Due to their nature and reason for being, OEM keys are distributed to companies in order to activate a limited number of computers through an agreement signed between Microsoft and the corresponding company. Imagine that you are the IT department of a company that has to install Windows on 500 computers. It would be crazy to assign a different password to each computer. Therefore, Microsoft assigns the same key to make it easier to install Windows on all those computers.

Of course, it is assumed that this key cannot leave the company or be used for another purpose. If the client company leaks one or more keys or the agreement between the two companies ends, Microsoft will permanently invalidate the use of this key , which will make its use on the computer that has been activated no longer valid.

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This means that if the key you have purchased belongs to this type, it may happen that at any given moment Windows 10 is no longer active on our computer, which is why we will have to acquire a new key, which must be Retail. . This policy is also applicable to other Microsoft products such as Microsoft Office . Any Office license sold as an OEM key can be deactivated at the end of the agreement or the activation period with the corresponding company or entity.

Windows 10 OEM vs Retail licenses, what are the differences?

In contrast to OEM keys, Retail keys are totally legal keys whose distribution is not delimited by any type of contract. Its sale, in fact, is totally legal , and it is the type of keys that Microsoft sells today in its official store, as well as in the rest of authorized sellers and distributors.


The difference in functionality between an OEM key and a Retail key is that the latter cannot be used on more than one computer. Once activated, it will become part of the equipment where it has been used through what is known as “BIOS recording”, which is why it cannot be used on other computers .

As for the Retail type keys, these can be transferred to another team, but what you cannot do is have it active on two or more teams at the same time. This is especially useful if we change equipment or we want to decide to activate a version of Windows 10 in a limited way, but not before deactivating the original key of the "source" computer to install it later on the "destination" computer.

Finally, it should be noted that while the OEM keys can be deactivated at any time for any of the reasons mentioned above, the Retail keys remain active forever , so we will not have to acquire other complementary licenses.