Modern game keys are complex, encrypted strings generated only by the game's publisher (Microsoft). An external program cannot "guess" a valid key that the Microsoft servers will recognize.
These tools often contain "trojans" or "cryptojackers" that use your computer's power to mine cryptocurrency for hackers. Forza Horizon 3 CD Key Generator -PC- XBOX ONE-
Since the game is no longer for sale on official storefronts, you have three legitimate paths: Modern game keys are complex, encrypted strings generated