In the fridge, in a plastic bait box divider. That way I can keep it somewhat organized. Skunk compartment, sativa compartment, hybrids, indicas, and singles is how I keep some order. I just leave them in the little plastic bags they arrive in. They can last years in the fridge, without a loss of vigor. Freezing can make seeds last a few decades. People have seeds over 20 years sprout no problem. I would not count on all to last that long, but some certainly will.