For a cookie based "remember me" function on a web app the user can choose to stay logged in for X days:
What do you think is better:
a) set the expiration time of the "remember me" only at first login, so the cookie expires after X days after the first login?
or
b) re-set the expiration time each time the user logs in, so the cookie would expire X days after the last login?
What do you think would a user expect?