The probiotics in Provitalize are freeze-dried, but the process does not affect their potency and allows them to be shelf-stable without refrigeration.
Freeze drying is a widely used method to stabilize probiotics or LBPs, which removes water from the microorganisms to achieve preservation of their viability, metabolic activity, and improve the storage stability of the products.
The probiotics within Provitalize are meophiles. A mesophile is an organism that grows best in moderate temperature, neither too hot nor too cold, with an optimum growth range from 20 to 45 °C (68 to 113 °F).
As the probiotics are freeze-dried, they reactivate upon contact with both the appropriate temperature and water. This should only occur after ingestion. The average human body temperature is 37 °C (98 °F).
The live cultures you see elsewhere, which require refrigeration, are known as psychrophiles. This means they thrive best in cold temperatures.
This is why Provitalize doesn't require refrigeration.