How long past expiration date can you use applesauce?

It shouldn't be used at all past the expiration date. Take another look at the code date on the package. Shelf-stable canned items are generally marked with a 'sell by' or 'best if used by' date, not an expiration. The usability of the contents will depend upon how how far past expiration it has gone, how the product has been stored and handled and whether or not the seals are intact. Even food in perfectly-sealed cans will degrade over time. The date that the packer has placed on the container is a guide for when it should be used for best quality.