With port, madeira, and stouter sherries, such as olorosos, palo cortados, and all creams, a period of one week to ten days is the absolute maximum that they should be allowed to remain open. Once the seal is broken, fortified wines become quite vulnerable. As far as distilled spirits go, no bottle aging is required. Once a whiskey, brandy, white spirit or liqueur is bottled, the maturing process ceases. All maturation occurs in the oak cask or holding tank.
Distilled spirits are ready to be consumed immediately.
Once you've opened a bottle of Scotch, bourbon, brandy, liqueur, or white spirits, it will remain drinkable for up to a year in most cases, but only if you keep it well sealed and out of heat and direct light. I personally don't leave bottles of spirits unconsumed for longer than two to three months at the very longest. I notice dramatic differences after a month or more. As far as storage for distilled spirits goes, I prefer to keep my best spirits in the cellar until they are open. Excessive heat is not good for any type of alcoholic beverage even if it remains unopened.