Double-wrap the cake tightly in greaseproof paper then foil and store in a cool dark place. It should keep for up to three years (the top layer is traditionally kept for the christening of the first baby). The icing and marzipan will last around three months. If you want to store the cake for longer, keep the icing and marzipan on until you're going to eat the cake and then replace with fresh before using. If the cake seems a little dry, drizzle a little more alcohol over it.