Activating this trainer:
Press F1 at main menu.
Listen for 'Trainer Activated'.
Press desired hotkey. All hotkeys can be changed on the trainer.
NumPad1: Infinite Health
NumPad2: Change EXP By 500
NumPad3: Change Funds By 5000
NumPad4: Change Quantity Of Selected Item By 5
NumPad5: One Hit Kills
Selected Item: Quantity
EXP / Funds: Open the ingame menu and click on 'Quests' tab, press hotkey. Close the ingame menu and open it again and click on 'Quests' to see it has changed. You automatically level up once you got enough EXP.
Quantity Of Selected Item: Open your inventory and MOUSE HOVER the item you want to add quantity to. Press hotkey, close your inventory and open it again to see it has changed.
One Hit Kills: While active most enemies can be killed by a single hit. Please note this does not work for all enemies (i.e. animals).
Unlock more trainer options including updates from here - Nier: Automata Trainer