Install Win10 display is not activated and can not be activated with the official KEY solution

Fans of the Win10 system can't wait to install the Win10 preview. However, some users report that they have not been activated after installation. It is also invalid to use the officially released KEY activation. Why is that? How to solve?

There are two versions in Windows 10 Technical Preview, one is Windows Technical Preview and the other is Windows Techinical Preview for Consumer. The activation key can only activate Windows Technical Preview. If you install the version, Windows Technical Preview for Consumer, you need to find the Add feature to Windows Technical Preview for Consumer in the Control Panel, select “ I have purchased the product key”, enter the Microsoft Open Technology Preview Key: NKJFK-GPHP7- G8C3J-P6JXR-HQRJR, the next step after successful key verification.
It turned out to be the case, and now it is clear that the ins and outs of things. Now I know that I can't activate the solution after installing Win10.