How should I store this oil after opening, and how long does it last?

Cold-pressed oils are more vulnerable to oxidation than refined oils because they retain natural antioxidants and polyunsaturated fatty acids (like linoleic acid, omega-6) that react with oxygen and light. Once you open the bottle, store it in the refrigerator with the cap tightly closed. The cold temperature slows down oxidation significantly. Aim to finish the bottle within two months after opening — the oil will not spoil suddenly, but its flavor, aroma, and the stability of bioactive compounds (silymarin, tocopherols) decline as oxidation progresses.

Before opening, keep the bottle in a cool, dark place away from direct sunlight and heat sources. If the oil starts to smell or taste bitter, sharp, or paint-like, it has gone rancid and should not be consumed. Buying a smaller bottle (like this 250 ml format) is a practical choice if you use the oil occasionally, because you will finish it while it is still fresh.