A legitimate license key transforms the software from a trial version into a registered version. This registration removes user limits, grants access to advanced features, and entitles the user to technical support and future updates. The key is specifically tied to the version purchased; for example, a license for CCProxy version 8.0 may not be valid for version 9.0 without an upgrade fee. This version-specific validation ensures that the developer is compensated for ongoing development and maintenance.