I need help with log-out/sessions issue

I’m using the PHPmotion script, with a use-a-credit to view-a-video mod. When the user logs out, the viewed video should not be available again to view, until he logs back in and chooses it, via a credit, but it is still available when he logs back in. Any ideas on what file may be responsible for what I guess you could call ‘clearing the session’?
Any guidance will move me towards a remedy, thanks

Have you tried unsetting any session variables that were set? Have you destroyed the users session on logout? Check out http://www.w3schools.com/php/php_sessions.asp