After around 4-5 years they start to lose their nutritional value... but they are still edible. They won't go bad as long as they were processed correctly and are still sealed. However, I would be very careful eating home canned foods not done yourself. Botulism is a real thing. You don't know how they processed those potatoes... if they did it properly, then they are fine. If not, they could kill you. Are you willing to take the risk?