If you are using a physical DVD:
Manual activation is an offline fallback method to activate GTA IV when automatic online activation fails. It was most common during the era. Instead of entering a product key online, you generate an installation ID (on your PC) and receive a validation code from Rockstar’s website or phone system. gta iv manual activation
By default, GTA IV includes a manual activation helper. Navigate to the game’s root folder and locate: If you are using a physical DVD: Manual
Before starting, ensure you have the following information ready: gta iv manual activation