the.com/payoff

means The final result or reward that makes everything leading up to it worthwhile — or, less charitably, a bribe handed over to make a problem go away.

from A straightforward compound of 'pay' and 'off,' first used in the literal sense of settling a debt or paying workers their final wages when a job ended. By the early 1900s it had picked up its slang criminal edge — the bribe that closes a crooked deal — and later its narrative sense, the point where a story 'pays off' the investment of attention you put into it.