How long a lemon lasts can depend on a few factors, such as how long they were already at the grocery store, where you are storing them, etc. Generally speaking, lemons can last roughly a week at room temperature and for two to three-plus weeks in the fridge.u003cbr/u003eu003cbr/u003eIf you find your lemons are starting to go bad, you can juice them and freeze the juice. The easiest way to do this is to pour your fresh squeezed lemon juice into an empty ice cube tray. Once the lemon juice is frozen, you can put your frozen lemon juice cubes into a Stasher sandwich bag or another freezer-safe storage container.