you should probably do that
if its opened already, you have yeast reactivating its production
while it'll make it stronger by abc, but the other ingredients that made it taste great will 'stale out'
if its an actual 'Beer' that hasn't had its yeast 'neutralized' and is greater than 8%abv. It'll actually mature better than wine
but if its a liquor, like rum, and ya don't balance it with something with citrus (Vitamin d) (funny long story in finding about how to end scurvy)
ya'll get a risk of some impurities that'll lead to pseudo-blindness and food poisoning. The same of the impurities that they normally siphon out during the brewing will reoccur because the re-population and cultivation of yeast cells once 'new atmospheric air' is introduced to the culture ('culture' being attributed to what is called a bacteria sample allowed to grow inside of a 'petri dish')
Funny thing about yeast
Yeast is so.... 'sensitive'...
about where it lives, what the summers and winters are.
how "wet" it is
or how "warm" or "cold" it is
that's the indie Beer brewing industry "in a nut shell" right now