How long will an opened bottle of Caesar dressing keep in the fridge?

It’s hot. I want to make a salad for supper tonight.

I don’t use Caesar dressing that often, and when I do I usually end up buying a new bottle because the open one tastes slightly sour to me. But Caesar dressing does taste slightly sour. I hate to throw away the one I opened in April, but is it still good?

And will it still be good in December?

Is there a better test than my uncertain taste?