Most types of liqueur will last as long as other spirits, almost indefinitely. However, a bottle of liqueur that's been open for a while may not provide a flavor as strong as a newer bottle. Cream-based liqueurs like Bailey's will spoil over time, and they usually have an expiration date on the container. Some liqueurs have crème in the name, but they don't actually contain cream. These drinks, like Crème de Menthe, can also last for a long time.