How long formula milk last once drink

Hi mummies i have question regards to formula milk. Once made, can leave 2 hours if untouched, 1 hr once drink bt never finish. Cs sometimes baby cry then when i make milk alr he suddenly sleep or etc. By 1 hr, if it exceed the 2hr time period ? Eg i make milk 1pm but baby only drank at 230pm, and didnt finish. Will the milk only last till 3pm or 330pm ? Is it max 2hrs after making the milk (3pm) or 1hr after start drink(330pm)?