miso- how long does it "keep"?

thank you Gilbert, it was intereting to learn all that-

Good long term fermented (2 years and more) and non-pasteurized miso has a pH of 4.6 - 4.8, relative humidity between 48% and 52 % and a salinity rate of 8 - 11 % : these conditions make it suitable for very long conservation. At least 3 years in the fridge and 6 months at room temperature (the official labs says that "it is non potentially dangerous!"). For such a long period as 8 - 9 years, it may have dried, darkened, gotten stronger and the taste may be quite more acidulate. You may smell and taste it and see if you still like it. If white or blue mold has developed on the surface, just scrape it away, smell again and taste. Miso is safe food.

When I was first in the natural food business, and macrobiotics was the thing, the word was that miso keeps indefinitely without refrigeration. At that time, we sold wonderful artisan miso from Japan in bulk, packed in a wooden tub. Now it's all refrigerated and use-dated. Like most things, the truth probably lies in between. If you think of pre-refrigerator Japan, it was probably kept in a cool-ish place, and used within a moderately short time.
So I would suggest, made a pot of wonderful miso soup or the miso-almond sauce every night, taste to see if it might need more than called for -- and then replace it with some of the tasty varieties now available.

If it has literally been 8 or 9 years (and I wouldn't judge you if it has), I'd chuck it and buy some fresh. But if it's been more like 6 months, I think you're probably okay. It probably won't hurt you if it's older, but it tends to start losing its flavor after a while.