Since Windows 7 is "End of Life," you are essentially buying a "New Old Stock" license or a surplus retail key.

: Ensure the seller provides a link to an official or verified ISO (disk image). You can also use tools like TechBench by WZT to find original Microsoft files. 🛠️ How to Verify Your Purchase

Buying legacy software requires extra caution to ensure you don't end up with a "grey market" key that fails.

Once you receive your key, you should immediately check its authenticity:

💡 : If you are installing on an old laptop, check the bottom of the device for a COA (Certificate of Authenticity) sticker. If it's there, you already own a license and just need to download the matching ISO version.

: Tie strictly to the first motherboard they are installed on and cannot be moved.

: If a site is selling just the 25-digit code for under $5, it is likely a volume license meant for businesses, which Microsoft can deactivate at any time. Look for "Retail" over "OEM" :