Hi Bäretta! It makes me smile that miso jars are sitting in the fridge in Chech.

Can miso go bad? I don't know. It is fermented, So it is spoiled already in a sense. I never heard miso went bad. But it does have an expiration date.

Miso can be fermented for 3 years in a air-tight jar in a shelf. But it can be molded (but mold can scraped off and the rest is fine). But if it is mixed with air and other food, it may go bad, I imagine. My friend actually put miso in the freezer. She said it would not be frozen and stayed as it is.

Unfortunately, I cannot say if your miso is fine for sure, But if it tastes the same, probably it is ok.

A small amount of miso can be added to dressing too.