• Dividing into portions with backing paper
• Roll and flatten them back to the “original” shape and place them between some wax or baking paper, store inside a zip lock bag
• Keep in a PET (polyethylene) plastic container away from UV light.
• Store in plastic container but discard after 1 year
• Try greaseproof paper as it’s similar to the original packaging
Some untried suggestions were between sheets of overhead transparencies, laminated paper, or alfoil. Also chilling it in a freezer shortly before use so it’s less sticky, which works for removing chewing gum.