Joe Haldeman’s 1989 Buying Time (also published as The Long Habit of Living) is a stand-alone science fiction novel.
The Stileman Process delivers immortality on the installment plan. In exchange for a million dollars (or all of a person’s wealth, whichever is more) the Stileman Foundation restores youth and vitality … for about ten years. Without another round of the Process, death swiftly ensues. It’s strong motivation for would-be immortals to keep earning fortunes.
Dallas1 Barr is adept at making money. What he needs now is a talent for running away.