Store covered in the fridge for several months. (The acid will cause metal to rust, so a jar with a metal lid is not recommended.)
Shake before using as it separates.
High quality olive oil will solidify in the fridge. To remedy this, place the salad dressing container in wider, but shorter container. Run cold water into the larger container, gradually turning the water to a warmer temperature. Let the dressing sit in the warm water until the oil thins out. This should only take a minute or two.