How long does Hennessy etc stay good for after opening? ?

how logn does it stay fresh along with smirdoff and hypnotiq|||booze never goes bad as long as it is not exposed to extremes|||it never tasted good to me in the first place but i keep light liquors like vodka in the freezer and hypnotiq in the fridge. but i would say the hennesey should be good for at least a month|||Keep it in a dark place, like a cabinet, or the fridge or freezer. Keep it closed tight, and it should last for many years.