Re: User\'s security administration
You cannot do this through OneWorld (it seems that unofficially, when being audited, multiple user logins by the same ID are not counted as multiple licenses by the way) - however, it is a problem especially with the way that certain temporary files are written to.
If you are a Citrix customer, you can prevent this by ensuring you are on Feature Release 2 - and under the published application properties, ensuring that the checkmark "Allow one instance of application for each user" is checked under the "Application Limits" tab.
You can also set up maximum instances to match your OneWorld licenses - and you can monitor this through the Resource Manager, which you can set up to write to a SQL Database. All in all, Citrix offers a lot of flexibility to managing who logs in and when.
As for the web client - I think you should be able to limit the number of concurrent sessions relatively easily on the web server.