I have a little network of a couple of machines at home, and I need to shutdown them at a certain hour. I found out that Windows 7 from Pro upwards offers a graphical Security Policies editor, where it's possible to allow the remote shutdown, but apart from mine, the other PCs have just Home Premium, which doesn't have the editor. I found out that the key is editable without the need of the editor, but how, and where do I find it? Or, are there any other ways? Thanks for the help.
I have never done what you are trying to do in regards to remote shutdown, but here is some information that may be useful:
Are you using the group policy editor for Windows 7 Pro? I believe that's gpedit.msc, right? Back in the day it used to be that you could use regmon (a Sysinternals program) to monitor registry keys that are changed, but it looks like Microsoft bought out Sysinternals and then retired Regmon. However, I believe they moved the functionality to Process Explorer (edit: turns out it's Process Monitor):
Monitor: http://technet.microsoft.com/en-us/sysinternals/bb896645
Explorer: http://technet.microsoft.com/en-us/sysinternals/bb896653
On your Windows 7 Pro machine run process monitor and set it up to monitor registry changes for gpedit.msc. Then change the setting using the program. Once you have the key you can document it or export it using regedit. I'm not sure how you plan on changing the registry key remotely, though.