You have to install Windows 10 as there is no direct upgrade for the Windows Embedded operating systems. Windows 10 Pro is for desktop systems. For those on XPe, WES7, WES8, Windows Embedded 8.1 Industry, Windows 10 Enterprise LTSC (aka Windows 10 IoT Enterprise)
is the Windows 10 version to move too. Windows 10 Enterprise LTSC has 10 years of support. Please take at look at the following article:
http://www.annabooks.com/Articles/Articles_IoT10/Windows-OEM-LTSC%20Rev1.2.pdf
Please contact your Microsoft distirbutor for more information.
Sean Liming - Book Author: Starter Guide Windows 10 IoT Enterprise - www.annabooks.com / www.seanliming.com