An information processing system includes at least one information processing terminal and a first information processing apparatus. When an instruction for selecting a user authentication mode, which is received, from a user, by a user interface of the information processing terminal, selects a second user authentication mode, circuitry of the first information processing apparatus determines whether a sum of charges for services used by the user while logging in the information processing terminal via the second user authentication mode after a most recent login via a first user authentication mode exceeds a predetermined amount, and generates an authentication result indicating that the user is not the authenticated user.