4D 2004 now allows the purchase of either a client Web Services expansion license or client Web Server expansion license. This gives the flexibility of using two different client machines and have them exclusively serve web pages or publish web services. In order to distinguish which client obtains which license, you will need to create groups.
Below is a snapshot of two groups created:
As shown above, the plug-in section of the group theme displays the licenses. Simply enabling or disabling the check box to the corresponding plug-in will restrict the use to the chosen group.