I am very...very new to baking and decorating cookies. On the 12th I made a bacht of mmf but only use 1/2 of it, I put the rest aside and forgot about it, I found it today! 
It is well wrapped with film wrap and in a plastic container and it has been in room temparature.
I would like to know if I can still use it? I only make cookies for family and friends. Thank you for your answer! 
I use Rhondas MMF recipe and if you have it well wrapped with plastic wrap and in a container it is still good to use, I have some in refrigerator and some in an airtight plastic container in my cupboard and both lasts for quite awhile.
cheatize, I use a recipe given to me by my teacher which is very simple
1.- 1lb mini marshmallow
2.- 2tablespoon of water
3.- 1/4 of crisco
4.- 2lbs of podwer sugar(publix)
5.- 1 teaspons vainilla
It does not have any perishable ingredients. It is very delicious.
Everyone I gave one of my cookies love them, and one of my brothers is very picky and he also said it was very good and also looked very pretty. I have not posted the cookies I made with this fondant, I have been very busy! I will post them later. I have the recipe in my computer and the procedure.
Sugarlicious, I will look for Rhonda's recipe to see if it is similar.
Thank you both for your time.
CIAO
I asked about the taste because sometimes my MMF should still be good (none of the ingredients I used to make it are expired and all ingredients are shelf stable) but it tastes bad. My general criteria for whether it's usable or not is:
Are the ingredients shelf stable?
Are any of the ingredients close to the expiration date?
Workability
Appearance
Flavor
If all that's okay, it should be fine to use.
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