Discounted Windows activation keys, sold at prices significantly lower than Microsoft's official rates, have sparked debate about whether they are a legal option, a scam, or a gray market that Microsoft might reluctantly accept. These keys, often sold through physical stores, traditional payment methods, and fast shipping, activate Windows in the same way as official keys, allowing the system to function normally, receive updates, and access the same features. The price difference is striking—some keys can be purchased for as little as 25 euros, while Microsoft asks for 145 euros. A Windows activation key is not the same as a license. The key is a 25-character code used to activate the operating system, while the license defines the rights to use Windows under Microsoft's terms. These two usually go together but can diverge. A Retail license, for example, can be transferred to another machine, making it flexible but more expensive. In contrast, an OEM license is tied to a specific machine and cannot be moved freely. Volume licenses are meant for organizations and are not intended to be sold individually. European law, particularly a 2012 ruling in the UsedSoft versus Oracle case, established that a software publisher who sells a copy with a perpetual license loses the right to control its distribution after the first sale. This principle allows the resale of second-hand licenses but prohibits the splitting of a single license. This legal framework has shaped the current dispute between Microsoft and ValueLicensing, a British reseller that buys perpetual Windows and Office licenses from companies and resells them on the second-hand market. In November 2025, the UK Competition Appeal Tribunal ruled in favor of ValueLicensing, allowing the resale of parts of volume licenses. Microsoft appealed, but the Court of Appeal rejected the appeal on July 7th. Microsoft is now seeking a review by the UK Supreme Court, which has paused the main part of the proceedings pending a decision. Second-hand licenses can pass through multiple hands before reaching the final buyer, allowing for price reductions. However, it is often difficult to trace the exact origin of the key. Alongside legitimate second-hand licenses, there are also stolen or counterfeit keys, which can be hard to distinguish at the time of purchase. A working key does not necessarily guarantee the seller had the right to sell the corresponding license. Microsoft has not provided detailed information on the origin of these discounted keys, their possible deactivation, or the measures it takes to limit their circulation. The company emphasized that license compliance and key activation are different, and that keys from volume licenses are intended for the organization to which they were assigned. It also noted that stolen or counterfeit keys can be refused or blocked. Microsoft recommends purchasing from itself or "trusted partners," but does not offer a directory of verified resellers. The company has not addressed the extent of the gray market or the reasons behind its persistence, a discretion that may be related to the ongoing legal dispute with ValueLicensing.