Cooked french fries will last from 2 to 5 days in the refrigerator before they start to grow mold and go stale.
If you're not gonna eat the cooked french fries within a few days you should freeze them and they will last 6 months to a year when frozen although the will lose their freshness.
As for uncooked french fries those should last a few days to 5 days as well before going bad and if you need to keep the uncooked french fries longer than 5 days you should also freeze them and they will keep for 6 months to a year too.
It's best to cook the french fries before 6 months for the best taste and freshness however they will last a bit longer than that as long as you freeze them whether cooked or uncooked.