by default PDFCreator will use the IE settings for the proxy.
If you have a limited amount of machines, the easiest solution is to use the offline activation on all machines, which will be valid for a year or until your current license expires.
Otherwise it might be possible to prevent PDFCreator from going through the proxy by creating the key HKLM\SOFTWARE\pdfforge\PDFCreator\LicenseServerProxy, containing a string "Url" with an empty value.
This is the only place PDFCreator will check before using the IE user settings, but I am not sure if an empty value will cause it to not use any proxy, so far it has only been used to specify a different proxy.
My IT says that when I try to activate it use the proxy (defined in IE options)
We try to add an exception to license.pdfforge.org in the proxy.pac : Same problem !