If you have an old laptop or desktop with a Windows 7 or Windows 8.1 sticker, that 25-digit key will often work to activate Windows 10 during the installation process. 4. Link a Digital License

: Look for reputable third-party sellers that offer OEM (Original Equipment Manufacturer) keys, which are often much cheaper than retail versions.

: You get a 100% legal, safe, and fully functional operating system that receives all security updates. 3. Reuse an Old Windows 7 or 8.1 Key