Cheats in Red Dead Redemption (original PS3/Xbox 360/PC) are session-only. They disable automatically when you:
Use a trainer (Cheat Happens, FLiNG) to freeze money, health, ammo, etc., without disabling achievements (if trainer supports “stealth mode”). Or use Save Editors to modify money/items directly.
Best Practice: Play a clean save for achievements; keep a separate “cheat save” for fun.