This site's own buyer checklist states this directly: refrigerate for probiotic stability — sources recommend refrigeration to help preserve the live probiotic strains.
Live probiotic strains like Bifidobacterium infantis, Clostridium butyricum and Akkermansia muciniphila can be sensitive to heat and humidity — worth following this refrigeration guidance to help protect the formula's live bacterial content over time.
Store your bottle in the refrigerator once opened, and take one capsule daily with an 8oz glass of water, per the label's own instructions.