'Unless' in the Bible

Remember then how far you have fallen; repent, and do the works you did at first. Otherwise, I will come to you and remove your lampstand from its place—unless you repent.

Look! I will throw her into a sickbed and those who commit adultery with her into great tribulation, unless they repent of her practices.

so that no one can buy or sell unless he has the mark: the beast’s name or the number of his name.