After you cook French Fries the cooked French Fries can stay out at room temperature for a maximum of 2 hours before they start going stale and bad.
If you want to keep the cooked French Fries longer than a few hours then you should refrigerate them and when refrigerated they will last up to 5 days in the refrigerator.
Uncooked French Fries will also last around 2 hours at room temperature once they are thawed out before they start going bad.
If you're not cooking the rest of the frozen French Fries then you should immediately freeze the rest of the French Fries to prevent mold growth and prevent them from going bad.
The bacteria can also grow pretty rapidly on the French Fries even if they are cooked and if the French Fries have been left out longer than 2 hours even if they are cooked they really should be thrown out because they could make you sick.