Is your Windows license legal? Should you even care?

If activation doesn’t prove you have a valid license, why does it exist?

We interrupt this story for some ancient history. Back in the late 1990s and early 2000s, software piracy was an existential crisis for Microsoft. Windows was the core of the company’s business, and independent local PC builders represented a disproportionate share of the Windows business. Unfortunately, a depressingly large number of those resellers bought a single license and installed it on multiple PCs. Microsoft created a network of activation servers designed to flush out “non-genuine” copies of Windows to prevent that sort of flagrant copying of retail and system builder packages.

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Hoo boy, did that go wrong. When I started at ZDNET, way back in 2006, I wrote a lot of words about the original Windows Genuine Advantage authentication software. I once called it “the stupidest thing Microsoft ever did with Windows”.

I long ago lost count of the number of words I wrote about Windows Genuine Advantage and product activation, but I don’t regret a single one of them. I know they made a difference. Microsoft removed the “kill switch” in Windows Vista Service Pack 1, and in Windows 7, the activation experience seemed to finally work.

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Over time, Microsoft discovered that it was in the company’s best interests to tolerate a certain amount of casual copying as part of its goal of not pissing off legitimate customers. I can’t remember the last time I received a complaint about product activation issues with Windows.

Today, the overwhelming majority of Windows PCs are sold by giant OEMs like Dell, HP, and Lenovo, which pay Microsoft for every license. (Even Microsoft’s own Surface division pays the Windows side of the house for Windows licenses!) Only a tiny sliver of PCs these days are built by hobbyists or small system builders. 

If someone in one of those groups tries to reuse a product key inappropriately (by activating multiple PCs using the same product key in a matter of days), the activation servers will object strenuously. But if you reuse a product key months after the first use, it’s likely that Microsoft’s activation servers will wave you right through.