The consensus is that Cognac can be stored upright in a cool dark place. No need to store it on its side or rotate the bottle. Once opened, the contents can evaporate slowly and the flavors fade, but you probably won't notice any change for months.

Should Cognac be chilled?

The Right Temperature For Cognac

Cognac should be drunk at room temperature. Do not heat Cognac as it destroys the flavors as the alcohol evaporates.

Can you put Cognac in the fridge?

Feel free to store unopened cognac bottles in a dry, dark space at room temperature for years at a time, as the cognac will not age in glass bottles. Meanwhile, opened bottles of cognac should ideally be stored no longer than six months, as the alcohol may oxidize and begin to lose its flavor.