We have the main Windchill server in Belgium and have users in different countries (companies) across the globe. During an assessment by PTC to whom his account the licenses will be counted ?
Windchill licenses are based on user name, they are not shared. Every unique user who connects to your Windchill system needs a dedicated license. Their location is irrelevant since Windchill licenses don't actually get installed, you just have to have a sufficient number of them.
Here are the actual licensing documents if you're interested.
As mentioned by Tom Windchill licences are based on the unique users connecting to Windchill. There is a utility "License Usage Reporting" which provides a way for administrators to view the peak number of concurrent users during a usage period, and whether or not that usage is in compliance with the number of purchased licenses. License Usage Reporting is available from the Site ▶ Utilities page.