If the feta cheese came in a vacuum-sealed package with brine (salted water), you can keep it in its original packaging. Simply reseal the package tightly after each use. The brine helps keep the cheese moist and preserves its flavor. If the feta cheese is not in brine or if you've removed it from its original packaging, place it in an airtight container. You can crumble or cut the cheese into smaller portions before placing them in the container.