For most people, Windows 10 is either a free upgrade, or it came on a new PC or laptop. If you’re ever asked for a product key – during a clean install for example – here’s what to do.

Microsoft is slowly phasing out product keys, as with the Windows 10 Anniversary Update you'll be able to assign a product key with your Microsoft account. However, if you're not on the Windows Insider Program's Fast ring, you'll want to extract your product key before 29 July 2016.

Read on to find out how to extract your key and the steps to take before upgrading your PC components.

Read next: How to upgrade from Windows XP to Windows 10.

How to find Windows 10 product key: Your product key is important

If you upgraded from Windows 7 or 8, Windows 10 will have activated automatically after connecting to Microsoft’s servers online. You didn’t need to enter a product key as you were entitled to Windows 10 by virtue of having a genuine consumer copy of Windows 7 or 8.

However, there are a few instances where you'll need your product key. If you've upgraded from Windows 7 or 8 and plan to upgrade your PC components, thus wiping your hard drive, you'll need your Windows 10 product key.

If you're installing a new system all together, then you'll also need your Windows 10 product key.

Both the above scenarios involve a fresh install of Windows, and despite Microsoft looking to release the Activation Troubleshooter tool within the Anniversary Update, you might be stuck between a rock and a hard place if you haven't already extracted your Windows 10 key.

You could even freely upgrade your system from Windows 7 or 8, extract your Windows 10 key and downgrade back to the older Windows versions. No matter your objective, we'll walk you through how to extract your product key.

How to find Windows 10 product key: Extract your Windows 10 product key

If you bought a PC, laptop or tablet running Windows 10 then it should have a sticker or Certificate of Authenticity which contains the product key, or be included somewhere with the packaging or documentation that came with it.

However, this isn't always the case. One reader told us that, according to HP, it does not put product key on laptops or PCs for security reasons. As with the digital entitlement, the product key is stored "somewhere in the computer" and will activate automatically if needed. This will work even if the hard drive fails.

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He said that the product key was semi-visible on the System screen in Windows: most is redacted with only the last 5 of the digits shown.

If you've purchased a boxed copy of Windows 10, it will be on a label in the box.

If you bought a digital copy of Windows 10 online from Microsoft, you should have received the product key in an email.

If however you've not got any of the above, you can always extract your Windows 10 product key using ProduKey, which is free software that displays your product key on various software installed on your machine.

How to find Windows 10 product key - ProduKey

Note: The program might be flagged by your anti-virus program, as it is a tool used to extract keys - some anti-viruses deem this as a virus or malware, but you can put your trust in us - it's safe. Read next: Best antivirus.

You should now write your Product Key on a piece of paper and store it safely. If you ever need to re-install Windows 10 on another machine or decide to wipe your hard drive, you can now install Windows 10 directly from a Win10 ISO. Read next: How to upgrade to Windows 10.

How to find Windows 10 product key: You don’t always need a product key to clean install Windows 10

Since Microsoft has your computer’s ‘digital signature’ from the initial upgrade it recognises the combination of components when you do a clean install and automatically activates Windows. This means you can safely skip the screen which asks for a product key at the start of the installation process.

It’s just frustrating that there’s no message to tell you this: the screen is only for those installing a version of Windows 10 they’ve purchased and which therefore still requires a key.

Windows 10 should activate as long as you haven’t made any major changes to your PC. Upgrading from a hard disk to an SSD won’t affect anything, nor will changing your graphics card. However, upgrading your motherboard and processor will probably count as ‘significant’ and you’ll have to ring Microsoft’s support line if you find that Windows is no longer activated, or you’re reinstalling it.

How to check if Windows 10 is activated

You can right-click on the Start button and choose System from the menu that appears. Under Windows Activation, you should see “Windows is activated”.

Similarly, if you click on Settings on the Start Menu, then Update and Security you will see a section called Activation. Click or tap on that, and you’ll see the edition your computer is running and the activation status.

How to find Windows 10 product key - Activation