How long do the olives last once jar is opened

2 to 4 months

Olives last a long time once opened. I keep mine in frig. They are brined (salted)

Should be a long time, depending on your tastes. Olive oil has preserved food since before the Roman Empire. Me? Those I bought yesterday are already gone. ;-)

They last just as long as any olives you buy in the store. Keep them refrigerated after opening and don'trump out the brine. The brine is what keep the olives from going bad. Your can expect 3-4 months easily when stored this way.

Mine are still good after 4 months in the fridge

Refrigerated, 4-5 months in brine.