Remember, this was used long before refrigeration was a thing. I know Crisco used to sell a lard, and it would sit on the shelf (with a plastic lid on it) for several months before it went bad. It had to be kept covered for sure, and over time it does go rancid - sniff test will let you know when it's past its prime. I used to make biscuits with it, you "cut it in" with the flour. Lard was also used (for example, in a mason jar) to store cooked meat. It would keep the meat from spoiling. (Place the cooked meat in a jar, pour in melted lard to the top, cover). I personally never used it to store meat so don't trust me on the details of that, I only saw a video once.