Understanding auth session lifetime

Using okta to authenticate to a single page site. Im wondering how the authentication lifetime is determined. IE When will an access to the page be sent to the login window again? Does the ‘lifetime’ get renewed with every access to the page? I haven’t found any API access to the authentication session data (beyond a base64 string) so I can’t see if there is a refresh token or anything of that ilk.

–EDIT–

nm - just saw the light. ‘a base 64 string’. Face palm.