A syrup that reads 100% maple syrup should generally be stored in the fridge. Because it's not made with preservatives, it's vulnerable to mold, making a fridge the safest option.
Exactly how long it will keep depends on packaging. Syrup in glass or tins keeps in the fridge for up to a year, but syrup kept in plastic will only last for three to six months.
If you want to keep syrup sold in a plastic vessel for longer, transfer it into a separate container since plastic "breathes." A glass Mason jar is a good choice for the job.
If you want to keep this silky topping around for a longer period of time, freezing it in a bag is also an option. Kept like this, it should stay good for as long as it's frozen.
Some maple syrups are hot-packed, which is a canning method that makes syrups shelf-stable. If your syrup was packaged this way, you can actually store it in the pantry unopened.