Storage

Seeds should always be kept dry, cool (close to 4º C if possible) and away from light.

The no-frost refrigerators are a good place to store seeds, preferably inside a film canister or vacuum-sealed in a plastic bag, to avoid moisture condensation.

In the absence of a fridge, seeds will stay viable at room temperature for 6 months to 1 year, sometimes more.
Try to avoid exposure to moisture, temperature changes or light.

The most important factors in storing seeds are temperature and light exposure.

For seeds it is really important that they are stored in a dark place with a constant or semi-constant temperature (ideally 4-7 Celsius).
Best place to store the seeds for periods over 1 month is in a no-frost refrigerator (with moisture control) at 4 degrees Celsius.
If stored in a no-frost refrigerator the seeds have a lifespam of 3 years, but beyond the three-year mark, their germination rate will begin to decline.

Sometimes seeds can stay viable for over 10 years, but it is a rare instance.