To keep this delicious cake fresh, cover cake with a lid if your cake pan has one or place some plastic wrap over the top. Place in the fridge up to 3 days. You can also freeze this cake. Wrap the cake with plastic wrap, then again with aluminum foil. Label it with the date you made it and freeze for up to 3 months. For best results, wait to add the whipped topping right before you are ready to serve it.