If making egg nog with booze, there is no fermentation. That's why its called "aged", not fermented. By three weeks the alcohol will have killed all microbes, good and bad. Hence, no need to use pasteurized eggs or
dairy. This may be how the old timers kept it. However, most say to keep it refrigerated while aging it. The alcohol also breaks down fats and proteins making the final product smoother. I'm making a batch now with eggs from my hens and since my goats aren't producing right now, goat milk from neighbors. Looking to make about 5 gallons as gifts for the holidays.