Corned beef rounds keep for about 5 days when stored properly in the refrigerator (should be fine if made with cooked corned beef). Store them wrapped tightly with plastic wrap on a plate covered by paper towels to soak any excess moisture that might otherwise accumulate under the plastic wrap. You can also store Corned Beef Rounds with all of their ingredients in an airtight container; however, they may absorb some the flavors from other ingredients and may start to taste sour or slightly bitter. Corned Beef Rounds do not need to be refrigerated if properly cooked. Keep them at room temperature for up to two hours, though they may pick up some flavors from the air as this time passes by. Corned beef rounds can also be stored in a freezer for up to 3 months.