Some users have reported problems with enabling their Windows 10 versions, which may have been the product of a variety of different reasons. In certain cases, buying a legal copy of Windows 10 is the best way to get around the issue.
Unlike earlier versions of Windows, the new one is almost entirely accessible online, which means that the best bet for your purchase is the official Microsoft website. The business gave away the OS free of charge, but that promotion stopped quite a while ago.
Microsoft has a useful website that provides either 32-bit or 64-bit versions of a downloaded copy.
If you notice that you are not able to successfully activate Windows 10, Microsoft has introduced a new activation troubleshooting feature in the Anniversary Update. In Settings, you will find this, then click Update & Security, go to Activation, and choose Troubleshoot (if the OS has been enabled, you won't see this option).