Properly cured ham, chorizo and salchichón can last foreeeeeever (specially if they’re not open). Spanish law currently requires all foodstuffs to be assigned a use-by date (not a “produced on” date); this date isn’t really linked to the time when the food in question is expected to turn bad (in the words of a cannery owner, “if a can is bad, it’s bad on day one, and if it’s not it’s not”), but to the legal requirement which basically was pulled out of the left elbow of a guy with a law degree.
The use-by date can be used to run “first in, first out”-type stock rotation schemes (“first expired out” is the specific one); since many of these products don’t have their production date listed, you can’t use that one.
One of the reasons the production date is not listed is - how do you determine it? Is it the day the pig was killed, the day the leg was hung up to dry or the casing stuffed, the day it was determined to be properly cured? A lot of brands are selling under-cured products, with the reasoning that “it’s more tender:” those brands definitely can’t use the third day, and if they listed the other two, it would scream “this so-called cured meat isn’t anywhere near cured.”