Sometimes “for ever” means, “age lasting” (e.g. Ex 21:6), but the majority of the time it means “without end”, and when you apply “for ever” to the age to come that does not end, “age lasting” during the an age that does not end means the same thing as “for ever”. “Age lasting” in an eternal age ends when the unending age does; that is, never. “For ever” applied to punishment (e.g. Jude 1:3, 2 Pet 2:17) refers to an age that never ends, and hence the punishment never ends. “The smoke of their torment ascendeth up for ever and ever: and they have no rest day nor night, who worship the beast and his image, and whosoever receiveth the mark of his name” (Rev 14:11).