QlikView generally releases RAM when it needs it, not before. So if you are watching memory usage in Windows Task Manager, you will not typically see it decrease as users logoff.
One thing you can do to influence QV to release memory earlier is to adjust the Document Timeout in the QMC. The Document Timeout indicates how long before a document with no sessions can be unloaded from memory. You can also set this in the Document Properties, Server, and the smaller of the two will apply.
It won't necessarily be unloaded right away, but you are allowing QV to unload the document if the memory is required.
