i've never heard of an expiration date. most extracts are done in alcohol, which preserves them indefinitely. i don't remember if vanilla is done in alcohol as well, but i know my grandparents would pull things like that out of the pantry that were years and years old and still use it.
herbs only have an expiration date because they are dry, and many lose their flavor or medicinal effectiveness after about 1-5 years. but that is not always true either, because i've encountered spice tins on archaeological sites that were 80 or more years old and could still identify what spice had been inside because it still smelled like cloves or whatever. so i have very little regard for expiration dates - they are mainly to scare us so we keep buying new things and keep the big companies in business.