How can the belief that Adam's Jannah was the Jannah of Eternity be reconciled with the Hadith of the عرض (presentation) of his progeny's ages to him, in which his age was specified, and what is the benefit of specifying his age while he was in Jannah?

The hadith states that Allah wiped Adam's back and extracted all his offspring. Adam saw the Prophet David, was impressed by him, and relinquished forty years of his life to him. The hadith does not mention that this occurred in Paradise; rather, there are indications that it happened on Earth. Furthermore, the Quran clarifies that Adam was not promised immortality in Paradise; instead, he was warned against expulsion from it. Satan's whispers to him about immortality suggest the absence of any divine promise to that effect.