How long does red cabbage last in a jar?

Hello,

So, last year before Christmas, I prepared what felt like a ton of red cabbage and canned it in jars. Now I have two jars left, and I wanted to use them up soon so I can make more before Christmas. I'm convinced it's still good. I learned from my grandmother that preserves can last for a hundred years. Still, just out of curiosity, I wanted to ask if there's a rule that says how long homemade preserves will keep.

Thank you in advance for all serious and useful answers 🙂