Upgrading from Windows 8/8.1 Home to Professional?
1. Download: http://go.microsoft.com/fwlink/p/?LinkId=510815
2. Open Up Media Creation Tool you just downloaded. Select your language. The Edition will be: Windows 8.1 Pro. For architecture, select either 32 or 64-bit. If you are unsure, select 64-bit.
3. Select the ISO option. Save to Desktop.
4. Once download completes, go to your Desktop and locate the completed file.
5. Right click and select "Mount." Run the setup.exe file and enter your key code when prompted.
6. Windows will run updates and restart in Windows 8.1 Professional.