Download guide

Windows 8.1 Pro 64-bit ISO download and activation guide (2026)

When you buy Windows 8.1 Pro from us, your order email includes your product key and a direct download link to an untouched 64-bit Microsoft ISO, so you don’t depend on Microsoft’s download page. Here’s how to download it, install it and activate it.

Windows 8.1 Pro ISO download: genuine digital licence

Get the key · $15.99
Windows 8.1 reached end of support on January 10, 2023. No more security updates. It’s suitable for offline use, older software or a virtual machine, not as an everyday internet PC. Most 8.1-era machines run Windows 10 Pro well.
Video guide · 5:57

Watch: download, install and activate Windows 8.1 Pro

Prefer watching? This video walks through the download link from your order email, the bootable USB, the installation with your key, and activation.

Watch on the KRBKeys YouTube channel →

Download the Windows 8.1 ISO from your order email

Your key and the download link arrive together in one email right after payment. Have the email open before you start.

  1. Open the order email from KRBKeys and copy your 25-character product key somewhere safe.
  2. Click the Download the ISO button in the email. It opens the file Win8.1_English_x64.iso on Google Drive.
  3. Click the download button. Because the file is large, Google Drive says it can’t scan it for viruses; click Download anyway. The ISO is a few GB, so give it a few minutes.
Can’t find the email? Check your spam or promotions folder. If it isn’t there, contact support with your order number and we’ll resend the key and the link.

Check the download (optional)

To make sure the file downloaded completely, open Command Prompt and run (change the path if you saved it elsewhere):

certutil -hashfile "%USERPROFILE%\Downloads\Win8.1_English_x64.iso" SHA1

The result should be a8b5df0b0816280ae18017bc4b119c77b6c6eb79. If it is different, delete the file and download it again.

32-bit or 64-bit?

The link in your email is for 64-bit, the right choice for any PC with 4 GB of RAM or more. The same ISO installs Windows 8.1 and Windows 8.1 Pro; your Pro key selects the Pro edition during setup. If you really need 32-bit for a very old machine, contact support with your order number.

Create a bootable USB

  1. Download Rufus and plug in a USB stick of 8 GB or more (it will be erased).
  2. Select the stick, click Select, pick the ISO, keep the defaults and click Start.
  3. Boot from the USB (F12 / F2 / Esc at startup) and run the installer. Pick Custom for a clean install.

Enter the key and activate

  1. Windows 8.1 setup asks for a product key before it will continue. Enter your 25-character Windows 8.1 Pro key here.
  2. After installation, go to PC settings → Activate Windows or press Win + R and run slui 3, enter the key again if asked, and activate online.
  3. If online activation fails, slui 4 starts phone activation.

Good to know

  • 8.1 Pro adds BitLocker, Remote Desktop host, Hyper-V and domain join over the standard edition.
  • Install drivers from the manufacturer’s site afterwards; the installer’s built-in drivers are from 2014.
  • Thinking of upgrading later? A Windows 8.1 key does not upgrade to Windows 10 or 11 any more; you’d need a Windows 10 Pro key for that.
Windows 8.1 Pro 64-bitGenuine key plus a direct ISO download link, delivered by email.
Get the key · $15.99