Quick answer: Download Windows 10 with Microsoft's Media Creation Tool, install it, then open Settings → Update & Security → Activation → Change product key and enter the 25-character key from your order email.
This guide covers Windows 10 Pro, Windows 10 Home, the Home-to-Pro upgrade key, Windows 10 Enterprise and the Enterprise LTSC 2021 and LTSC 2019 editions.
Important: Windows 10 end of support
Microsoft ended support for Windows 10 Home, Pro and Enterprise on 14 October 2025. Windows 10 still installs, activates and runs normally, but it no longer gets free security updates. Home and Pro users can enrol in Microsoft's Extended Security Updates (ESU) programme through Windows Update. LTSC editions follow their own, longer lifecycle (Enterprise LTSC 2021 is supported until 12 January 2027). If your PC meets the requirements, Windows 11 is the better long-term choice.
Before you start
- Windows 10 needs a 1 GHz processor, 2 GB RAM (64-bit), 32 GB of storage and DirectX 9 graphics.
- Back up your files before a clean install.
- Prepare an 8 GB or larger USB stick if you're installing on a new or wiped PC.
- Keep your 25-character key from the order email at hand, and check it matches the edition you're installing.
Step 1: Download Windows 10
| Edition | Where to get the installer |
|---|---|
| Home, Pro | Microsoft's Windows 10 download page (Media Creation Tool or ISO) |
| Enterprise | Install Pro from Microsoft's page, then upgrade to Enterprise with your key (Step 3) |
| Enterprise LTSC / IoT LTSC 2021 and 2019 | The installation link in your order email. Evaluation Center ISOs are trials that can't be activated with a key. |
Step 2: Install Windows 10
- Run the Media Creation Tool and choose Create installation media (USB flash drive, DVD or ISO file) for another PC. To upgrade the PC you're on, choose Upgrade this PC now instead.
- Boot the target PC from the USB stick (F12, F11, Esc or F8 at start-up usually opens the boot menu).
- Select Install now, then enter your key, or choose I don't have a product key to activate later.
- If you skipped the key, select the edition that matches it (Home or Pro).
- Choose Custom: Install Windows only, select the drive and let setup finish.
- Complete the setup screens and sign in.
Step 3: Activate Windows 10
- Open Settings → Update & Security → Activation.
- Select Change product key.
- Enter the 25-character key and select Next → Activate.
- Check that the page shows "Windows is activated".
Home to Pro, and Pro to Enterprise
Entering a Pro upgrade key on Windows 10 Home, or an Enterprise key on Windows 10 Pro, upgrades the edition in place. Your files and apps stay, and the PC restarts once.
Command-line activation (LTSC and Enterprise)
Open Command Prompt as administrator and run:
slmgr /ipk XXXXX-XXXXX-XXXXX-XXXXX-XXXXXslmgr /ato
Use slmgr /dlv to see the edition and licence status.
Troubleshooting
| Problem | Fix |
|---|---|
| Key not accepted | Make sure the installed edition matches the key. An LTSC key only activates LTSC, and a Pro key needs Pro (or use Change product key on Home to upgrade). |
| "We can't activate Windows" | Check your internet connection and try again later, or run slui 4 for phone activation. |
| Activation lost after new hardware | Use Troubleshoot on the Activation page while signed in to your Microsoft account. |
Still stuck? Reply to your order email with a screenshot of the Activation page and we'll help you.
Frequently asked questions
Can I still buy and activate Windows 10?
Yes. Windows 10 keys still activate, and Windows 10 keeps running after end of support. It just stops receiving free security updates unless you join ESU.
Can I upgrade from Windows 10 to Windows 11 later?
If your PC meets the Windows 11 requirements, you can upgrade for free through Windows Update. An activated Windows 10 Pro becomes an activated Windows 11 Pro. See our Windows 11 guide.
Which edition should I install for an LTSC key?
Install exactly the LTSC version on your key (2021 or 2019, standard or IoT) using the media from your order email. LTSC keys don't activate Home or Pro.
Useful links
| Link | What it's for |
|---|---|
| Windows 10 download (Microsoft) | Media Creation Tool and ISO |
| Windows 10 ESU (Microsoft) | Security updates after end of support |
| Windows 10 Pro key | Buy a Windows 10 Pro licence |
| Windows 11 install guide | Upgrading to Windows 11 |