Here are two document extensions that allow you to kill an AJAX session when the browser closes. These should be helpful in cases where you want be sure the resources get freed up right away after the user is done using QlikView. It has the same effect as the user clicking the "Close" link in the AJAX client, but now the user does not need to remember to make this click).
There are two document extensions included. "TerminateSession" will simply kill the session without user interaction when the browser or browser tab is closed. "TerminateSessionPrompt" will prompt if a user wants to kill the session when the user closes the browser or browser tab.
More details please refer to Community:Community Post
Remember, the actual API calls used are 100% supported, but the full blown extension is offered only as an example and is not supported.
Further explanations and install instructions are found in the attached .zip file in the article.
Document extensions are only available in QlikView 11 and later releases, so these will not work in Version 10 or prior releases.