.

Keeping this in view, does balsamic reduction expire?

If stored properly and taken good care of, balsamic vinegar doesn't go bad. Unless you've left the bottle opened and some contaminants got inside, balsamic vinegar doesn't spoil.

Similarly, how long does balsamic vinegar last? about 3 years

Also know, how long does store bought balsamic reduction last?

It tastes sweet, but it's still acidic as hell. On top of that, the reduction process is UHT pasteurization at its most basic. It'll last a long time in the refrigerator, three weeks or a month at least, as long as you didn't add anything weird to it. Note: in my mind balsamic reduction is balsamic vinegar, reduced.

Does balsamic vinegar reduction need to be refrigerated?

Storing your balsamic reductions: For long-term storage, refrigerate the reduction, which will maintain quality. But for a week or less, you can certainly keep the sauce at room temperature, it's not a safety issue.