General consensus is: if the source is legit and the packaging doesn't seem to be damaged, just leave it as it is, store in a cool, dark place and, most important, avoid contact with moisture. If you still want to be extra cautious, you can put the original packaging inside an additional ziplock bag.
Once opened for testing, the container shall be resealed asap as was originally packaged, the SN won't degrade that quickly once exposed to air unless you're in an extremely wet environment.
As for shelf life, if stored correctly it should last at least 3 years, but some people - maybe more knowledgeable than me - claim that its shelf life is indefinite if stored properly.