of homemade mmf?
I dont know what recipe you're using, but mine will keep well for weeks if wrapped properly I like to make large batches at a time so that I don't have to be constantly making fondant...as it can get quite messy and sticky
I think I saw on another forum somewhere that someone keeps theirs for 3 months.
I read on a different site that it's good for as long as the shortest expiration date. Whatever your ingredients are, the one with expiration date that comes up first is how long the fondant is good.
However, I don't do that. When in doubt, I pinch off a bit and taste it. The taste changes over time and when it does, I assume it's not good to use. Generally, I keep it about a month, well sealed.