It takes a lot to spoil maple syrup.  Unopened, it will keep for years in your pantry.  Even opened it can last months without refrigeration.

You may store maple syrup in your freezer to retain the flavor and quality over an indefinite period of time. The syrup will not freeze solid and will require only about one hour at room temperature to bring it to pouring consistency. The amount required can be removed from the container, and the remainder may be returned to the freezer and re-frozen without harm.

And amazing as Maple Syrup is…there’s more…

Per the FDA, if mold should form on the surface of the syrup, the original quality can be restored. Remove the mold, heat the syrup to boiling, skim the surface, sterilize the container, and refill it with the syrup.  It’s as good as new!