Scripture only specifically says that the Lake of Fire is eternal. This is different than Hades/Hell/Gehenna and is prepared for the absolute final things. Elsewhere, Jesus sometimes talks about the condemned in conditional terms. "Verily I say unto thee, Thou shalt by no means come out thence, till thou hast paid the uttermost farthing." - Matthew 5:26 . A very uncomfortable verse for those who equate all afterlife states with a strict either/or of Heaven or the Lake of Fire. Obviously Jesus meant something different here, unless you think Christ is careless with his words. I hope you don't.
I'll leave it you to make of that what you will. I'll just add that I'm not teaching Purgatory, but I understand why some Catholic scholars started teaching that. I just want people to think about it instead of repeating memes.
As for the Lake of Fire: "And the beast was taken, and with him the false prophet that wrought miracles before him, with which he deceived them that had received the mark of the beast, and them that worshipped his image. These both were cast alive into a lake of fire burning with brimstone." - Revelation 19:20
After the millennium, Satan is finally cast into it:
"And the devil that deceived them was cast into the lake of fire and brimstone, where the beast and the false prophet are, and shall be tormented day and night for ever and ever." - Revelation 20:10
TORMENTED.. forever and ever. Indeed it's eternal and not a mere consuming fire. But a tormenting fire. This isn't the conditional punishment Jesus mentioned earlier.
Finally death AND "hell" (yes, hell is noted as something entirely different than the Lake a Fire, and even an entity apparently) is cast after Satan. Then those not in the Book of Life are cast:
"But the fearful, and unbelieving, and the abominable, and murderers, and whoremongers, and sorcerers, and idolaters, and all liars, shall have their part in the lake which burneth with fire and brimstone: which is the second death." - Revelation 21:8