It does seem to keep forever if you wrap it well. Are you going to make the topper before you store it? It might be hard to really get it wrapped well—it might dry out but if no one is really going to eat it anyway that won’t really matter. If it looks dry you can brush it with a damp paint brush to refresh it a little.

I am planning to make a detailed fondant topper for a friend’s party but will be very busy the two weeks before-can I make it in advance and keep in in fridge in an airtight container? Or in the freezer?