In the bottom-right corner of your screen (overlapping your wallpaper), you will see a translucent text overlay: “Activate Windows. Go to Settings to activate Windows.” It does not appear over full-screen games or movies (usually), but it is always there on your desktop.
You can install and use Windows 10 without a product key, a significant shift from older versions like Windows 7 that would lock users out or reboot frequently after a grace period. Microsoft currently allows users to download the official ISO and run the operating system indefinitely with relatively minor restrictions. How to Install Windows 10 Without a Product Key windows 10 without product key
If you previously had Windows 10 activated but changed your hardware (like a new motherboard) and lost the activation, the Settings app has a feature for this. In the bottom-right corner of your screen (overlapping