However, if you don’t have the key and still you want to get rid of this problem. You can activate Windows using it and get back to your usual business. So, if you have the money, you get the key instantaneously from any authorized site or even from Microsoft. By activating Windows you will get Windows updates, security features, Windows Defender, and many more. Windows activation also brings in certain added features, which you won’t be able to avail of if you haven’t activated Windows on your machine. Although the key is 100% valid, the watermark is still visible because of the unmatched Windows 10 variant. Unmatched Windows version – If you purchased key for Windows 10 Professional Edition and you installed Windows 10 Home Edition on your computer.Microsoft uses online activation technology to block other users using the same product key. Windows License Invalid – You can input a key you are getting from online sources and it simply does not work because it has been used by others.Other than that, these are the reasons why There are varied reasons for it to appear, one of the most common reasons is when Windows is not activated/expired. Conclusion Reasons Behind Activate Windows Watermarkīefore jumping on to how to remove activate Windows watermark, you should know the reasons for it to appear on your screen.