Hardcoding and DRM
As an digital rights management measure, software developers may hardcode a unique serial number directly into a program. A program that has a unique serial number may regularly check its maker's website to verify that it hasn't been blacklisted as compromised. If that website moves or the company goes out of business, this may cause the program to fail, even for perfectly legal users, if that check is programmed to fail when no response is received.
On the opposite case, a software cracker may hardcode a valid serial number to the program or even prevent the executable from asking the user for it, allowing illegal copies to be redistributed without the need of entering a valid serial, thus sharing the same key for every copy, if one has been hardcoded.
Read more about this topic: Hard Coding