Per the facebook API docs:
In addition to the access token (the access_token parameter), the response contains the number of seconds until the token expires (the expires parameter). Once the token expires, you will need to re-run the steps above to generate a new code and access_token, although if the user has already authorized your app, they will not be prompted to do so again. If your app needs an access token with an infinite expiry time (perhaps to take actions on the user’s behalf after they are not using your app), you can request the offline_access permission.
I would like a Facebook.login() method that takes a token as a variable, one we stored on a previous session and registers to the listeners. This way a user could Auth once and any time they open the app they are already signed on. This is how apps like Words With Friends work.
Currently you must login with SSO or popup each time the user reopened the app. We also lack access to the expiration time so we don’t know when to refresh our current Facebook session.
[import]uid: 110373 topic_id: 20424 reply_id: 320424[/import]