as far as, as long as
Indicates a limitation based on certain conditions or the extent of something.
Examples
私が知っている限り、彼は無事です。
As far as I know, he is safe.
あなたが必要な限り手伝います。
I will help as long as you need it.
ここにいる限り、心配する必要はない。
As long as you are here, there is no need to worry.
Quick check
As long as you are here, there is no need to worry. ここにいる___、心配する必要はない。