Our cultures travel very well. Just store the items "as advised" as soon as possible.
Cultures are shipped to us from overseas and are not delivered in refrigerated transport, and we just store the items correctly once they get to us. It is the long-term storage that is important.
It is our experience that cultures shipped all the way to the northern parts of Western Australia, such as Broome and Karratha, from our location in SE Queensland at the height of summer, which can take two weeks and even longer to arrive are still viable.
We have shipped thousands of culture sachets a year for over a decade and have found the cultures are hardier than may be imagined. We tested yoghurt cultures left at room temperature over a period of four months. We found that at three months the culture still worked well, however; at four months we needed to increase the culture dose significantly. This same culture kept in a freezer would have lasted for years.
What we wish to avoid is anyone getting their yoghurt or cheese cultures or enzymes and storing them in the pantry for many months, without even knowing that they needed to be put in the fridge or freezer.
Perhaps we are overcompensating with the notes on our site and the labels all over the place, but we do know someone who kept an unopened cheese kit in a hot pantry for two years.