Saving sessions on my Insta gram Project

I have a web based Insta gram application I am writing myself. I need help with just one aspect of this project that I cannot get working right. It involves using PHP sessions. I can't seem to get this to remember or stick with my current registered session. When i first sign it, it works, but when i navigate to other parts of my site, it will forget. It finally will work after several minutes. Then the same for "logging out". I will log out and 'destroy' the session but upon re-visiting to my site it will think im already authenticated. This will require knowledge of the Instagram API, which I can help with since i've been working with it alot. Also im using the Cosenary Instagram API wrapper to make my function calls ([login to view URL]).