Brownies last three to four days at room temperature. Typically, brownies should be stored in the pantry in an airtight container. Brownies can be frozen for no longer than four to six months for optimal quality but remain safe to eat indefinitely when stored at temperatures below 0 degrees Fahrenheit.
While most brownies do not need to be stored in the refrigerator, those with icing made with dairy products need to be refrigerated. Refrigerated frosted brownies last around three to four days and need to be kept in an airtight container or wrapped in plastic wrap. Brownies with dairy-free frosting can be stored at room temperature for up to four days.