'Forever' in the Bible

I said to the king, "Let the king live forever! Why shouldn't my face be sad, when the city, the place of my fathers' tombs, lies waste, and its gates have been consumed with fire?"

On that day they read in the book of Moses in the audience of the people; and therein was found written, that an Ammonite and a Moabite should not enter into the assembly of God forever,