Following this video I have made pemmican. When making the pemmican I used a food processor instead of rocks (because I'm lazy). I handled it with care, and according to this handbook, this stuff will last years, but ... I'm not entirely confident that I can toss this in my pack for a week. How can I tell when it has spoiled? Does it look wrong, smell wrong...?
Lard/fat can last a long time without going bad if stored in a cool dry place, but it can still go rancid. The smell test is usually the easiest way of knowing if things have gone bad.