Why don't I need to enter a key to install Win10

Win10 in the installation of a little and win7/win8 is not the same place, is the upgrade from the old system to WIN10, is not required to enter the product key, after the upgrade, the system will automatically be activated (of course, if the original WIN7/WIN8 upgrade to WIN10). Why is this?

Microsoft has enabled a new activation mechanism called "digital endorsement" in Win10 that allows WIN7/WIN8 users to get upgrades without a product key. With the "digital recognition" mechanism, manual activation is required unless the motherboard of the computer is updated or a new WIN10 system is installed.

Digital recognition can be applied to the following four scenarios:

1. When you plan to upgrade to the WIN10 system on a qualifying device running the WIN7/8 system

2. You purchased the real WIN10 system from the Windows Store and successfully activated it on the device.

3. You purchased the WIN10 Pro upgrade from the Windows Store and successfully activated it on the device.

4. You are a member of Windows Insider and upgraded to the latest WIN10 Insider preview on a qualifying device that previously ran Windows and Win10 preview that was successfully activated

At the same time, the constant color also gives the circumstances under which the key is required:

1. You purchased a copy of a Windows 10 physical system from an authorized retailer

2. You purchased a copy of the Windows 10 digital system from an authorized retailer

3. You have a volume licensing contract for Windows 10 or MSDN Subscriptions

4. You purchased a new device that runs a Windows 10 system

This means that regardless of whether you purchased the WIN10 system genuine license from the store, you can reinstall without a product key. You'll be able to reinstall it, and the system will automatically execute the activation program.

Why don't I need to enter a key to install Win10