A game system includes a management apparatus and a game device. The management apparatus includes an authentication section for obtaining results of authentications using first and second identifiers that should correspond to a user. When the results of the authentications are affirmative, a validity time limit is associated with the first identifier. In addition, the game device includes a confirmatory identifier acquirer for acquiring a confirmatory identifier that should correspond to the user, and an inquiry maker for making an inquiry asking the management apparatus to check whether or not the first identifier conforming to the confirmatory identifier is stored in the management apparatus. The inquiry inquires the management apparatus to check whether or not the validity time limit corresponding to the first identifier is a time after the present time when the first identifier conforming to the confirmatory identifier is stored in the management apparatus. A permitter of the management apparatus permits execution of a service associated with the first identifier used in the inquiry when results of checks by the manager in response to the inquiry are affirmative.