It cannot do that, as it's just a code to enter on a perfectly legit shareware program. In the worst case, it'll just get rejected.
However, keep this in mind -
1. Most of these codes are blacklisted, meaning they used to work, but not anymore.
2. Using such codes, you cannot update your software, or the code becomes invalid. Not updating your software can have seriously dangerous consequences; it'll make your system vulnerable.
3. Don't ever do this for antivirus programs. Even if you pirate everything in your PC(I don't encourage that, mind you), this is one piece of software you SHOULD buy legally.
4. Some software have mechanisms built-in to detect such fake codes, and will alter your experience of how the software behaves. This is known as DRM(digital rights management). Examples include the drunk camera and spontaneous catching fire of cars in GTA 4.
5. The sites that you visit to download such codes from CAN infect your PCs with keyloggers, malware, adware and such programs. So better stay away from them.