I have a trial version of Windows 8 Professional that expires in February 2014. For my usage Windows 8 or Windows 8 Core versions are enough. It it possible to downgrade it to the normal non-Professional version of Windows 8 when I buy it officially? Do I have to re-install it completely or do I only have to enter the new registration code?
You can use this small tool called UpDown8.
Select which edition you want to downgrade: