Even the traditional type of balsamic vinegar can last for years if stored correctly. The process of making vinegar is the same as making wine, so it gains layers of flavor throughout the years. Modern balsamic vinegar can be consumed after it has passed its "Best-by" date, but traditional vinegar cannot. The main issue with commercial balsamic vinegar after this date is that its quality decreases gradually over time. Generally, it's best to use everything within three or five years after its "Best-by" date.