How long do seeds last if not used ?

I've been thinking about doing a small grow for myself. I have these Northern Light seeds which I bought at least one year ago and they've been sitting unused since that time. Are they still good to use ?

I will obviously find out when I plant them, but I wanted to know before I bought some items and I started to make my little grow box.

Thanks.

Here's an update to my question. I finally started to germinate some of my NL seeds and no luck so far. I think they might be too old. I found out that I purchased them about 2 1/2 years ago, so they were a little bit older than I first thought. I placed 4 of them in peat pellets in a dark cabinet and 3 in a mug of sterilized water on top of a cable box for warmth. The peat pellets are 5 days in and so far nothing, I've kept them moist, but not overly wet. The seeds in the water have sunk to the bottom after I tapped them, but no roots, cracks or anything yet after almost 3 days. I'll give both methods a few more days, and if nothing happens, I guess I'll just have to order some new, fresh seeds. I also bought a small cabinet for my grow, and I'll be ready to go as soon as I get lucky with germinating at least a couple of seeds.