Hi rvkvino,
if the user navigates to other page the Lightstreamer session should close shortly. Have you different evidences?
Instead in case of browsing through the tabs, it is common practice keep open the session, but if you want a different behavior you should be able to detect the blur and focus events for the browser window, closing and re-opening the session calling disconnect() and connect() of LightstreamerClient.
About restrict other person to view LS server please refer this document:
http://www.lightstreamer.com/repo/distros/Lightstreamer_Allegro-Presto-Vivace_6_1_0_20170123.zip%23/Lightstreamer/PRODUCTION_SECURITY_NOTES.TXT
that shows how to protect the Monitoring dashboard of the server and suggests to remove at all the "pages" folder.