Originally Posted by Criniit
I forgot to check on the extract can, does it have an experation date printed on there?
I've never used a cooper's kit before so I'm not sure if it will have an exp. date, the yeast should have either an manufacture date or an exp. date though.
If you're using DME, keep it dry and out of direct sunlight and it will last for a long time. I'm pretty sure that LME has a shorter shelf life but I've never had any sit around for longer than a couple weeks, so someone else may be able to better answer that.
Liquid yeast if stored properly(in the fridge) should last close to 6 months, but I'd try to use it within 3-4 months. Dry yeast will last quite awhile when stored in the fridge as well.