If you absolutely need this specific software (usually because you have an older camera not supported by NX Tether), here is the legitimate path:
A popular tool for both PC and smartphone that enables remote control and is often used by astrophotographers, mentioned in user discussions on How to Properly Use Camera Control Pro 2 If you choose to use the official software, Nikon Camera Control Pro 2 Product Key Free
For most modern Nikon users, the "proper" solution is no longer buying Camera Control Pro 2. Nikon has released NX Tether , which is free. If you absolutely need this specific software (usually