Open the tool before or after launching RE5, depending on the tool. For save editors: close the game completely.
If you are wary of third-party tools, you have two other ways to "unlock" the Gold Edition content: resident evil 5 gold edition unlocker
Unlocking infinite ammo for specific weapons requires two steps: fully upgrading that weapon, and then purchasing the "Infinite Ammo" bonus using Exchange Points gathered from finishing levels or playing Mercenaries. With multiple weapons per category, the cost to unlock infinite ammo for the entire arsenal can exceed 100,000 Exchange Points—a massive grind. Open the tool before or after launching RE5,
Most unlockers for RE5 function by interfacing with the game's configuration files or directly injecting into the memory to flag items as "Unlocked." resident evil 5 gold edition unlocker