Microsoft provides generous legal alternatives: free web apps, student licenses, low-cost subscriptions, and even unactivated Windows for indefinite use. For businesses, the cost of non-compliance with software licensing can be catastrophic.
You can download the official Windows ISO directly from Microsoft and install it without a key. While you will have a faint watermark on your desktop and lose some UI customization options (like changing the wallpaper), the OS will remain fully functional, receive security updates, and be completely safe to use.
If you already have a copy on your system, run a full antivirus scan (Microsoft Defender Offline or Malwarebytes) and consider reinstalling your OS to ensure no hidden persistence mechanisms remain.