License keys are first added to the repository in KSC.
C:\ProgramData\Kaspersky Lab\AVP[Version]\Data\ kaspersky license key file location install
If you have already activated the software and are looking for the physical file on your hard drive, it isn't stored as a simple, readable .key file. For security reasons, Kaspersky encrypts license data into the system registry and program data folders. License keys are first added to the repository in KSC