How long after opening that pimms must be drunk?

Once opened, a bottle of Pimm's should ideally be consumed within 3 to 4 weeks for the best flavor and quality. After this period, while it may still be safe to drink, the taste may deteriorate. It's best to store it in a cool, dark place and ensure the cap is tightly sealed after each use. Always check for any changes in smell or appearance before consuming.