We can lots of stuff and due tot the abundance of apples here in the western U.S., apple products are always canned. Applesauce is one of the easiest since it doesn't require cooking. We get about 12 to 14 quarts per bushel of average sized apples. I believe the sweeter the variety the better, but others like the tarter flavor of different varieties.
At any rate, in answer to your question, it's the canning process in a boiling water bath for about 35 minutes that preserves the sauce. We have sauce that is at least two years old and still good...
Best of luck!