Unopened olives can last up to two years depending on the type of brine method
. Brining is the preservation process used for olives. It is a salt-laden solution used to pack the olives. There are different methods of brining for different amounts of time. You can find your own brining methods online that will brine your olives from two weeks up to four months. If olives are opened they must be kept refrigerated and will last no more than a few weeks.