at the expiration of the period of one month(Example: This Act shall come into operation at the expiration of the period of one month beginning with the date on which it is passed. (Перевод: Настоящий Закон начинает действовать по истечении месячного срока, начиная с момента (или со дня) его принятия. Пазенко Георгий)
upon expiration(Proceeds received upon expiration or early termination of call options purchased to fund annual index credits are recorded as part of the change in fair value of ... Alexander Demidov)