Renergen (ASX: RLT) creates vaccine storage solution, page-7

form of carry case can sustain upto 30 days at the temperatures required for biological materials rather then liquid nitrogen which (4 days).

I can assure you that their claims about how long liquid nitrogen can be stored are incorrect.

Go into any doctrors surgery. They will have a dewar of liquid nitrogen which they use to burn off warts. It lasts for many many months before they need to refill it.

Or you could simply google:
"How long does a dewar or liquid nitrogen last"

I will leave that as an exercise for the reader.