Provided is a server including: a user authenticating unit that authenticates, using an access token, a user of a user device; a token receiving unit that receives an access token from the user device; and a determination information transmitting unit which, when the access token is received, transmits determination information that enables a determination as to whether or not a remaining time until a time of expiration of the access token is less than a predetermined threshold, to the user device, wherein the user authenticating unit issues a new access token with an updated time of expiration when an issuance request for an access token which is transmitted by the user device having received the determination information is received.