While wine collectors know that their investments are still maturing in the bottle, liquor owners don't get the same benefit from holding onto bottles for a long time -- or the same risks. Because of the high alcohol content of distilled spirits, they remain stable indefinitely, neither improving in character nor deteriorating. However, to remain stable, bottles of liquor have to be kept under the right storage conditions.

Liquor bottles should be kept at room temperature, away from direct sunlight or other sources of ultraviolet light. Light can bleach the label of a bottle, causing it to lose its resale value. Darker liquors such as whiskey may also lose some of their color through prolonged exposure to sunlight. Some whiskey distillers claim that natural colors fade more slowly than artificial colors, but it's still advisable to avoid direct sunlight.

Once a bottle of liquor has been opened, however, the clock starts ticking. Expert Ethan Kelley estimates that an opened bottle will only retain its flavor and character for six months to a year. Because contact with air causes the liquor to degrade, reducing the alcohol's exposure to air can help preserve it. This can mean decanting the liquor into a smaller bottle or even replacing some of the air in the bottle with an inert gas.

Unopened bottles of liquor are immune to the negative effects of contact with the air only as long as they stay properly sealed. Regular inspection will spot cases in which the cork might be deteriorating. A decreasing level in the bottle indicates that evaporation is occurring. Although liquor, unlike wine, does not need to be stored horizontally to keep the cork wet, occasionally upending the bottle can help make sure that the cork does not dry out.