The last demo we had at my branch of the BSG (British Sugar Craft Guild) was on chocolate work.
experienced) demonstrator said it will be fine in the fridge for a good 4 weeks.
However, there's more chance of me flapping my arms and flying to the moon, than managing not to eat any left-over ganache!!
Honestly? I'd taste some. If the cream's gone off, you'll know!!!
(ps did you know you can make ganache with butter instead of cream? This will keep in the fridge for up to 6 months!!!!)