A KLQ file is a quarantine file created by Kaspersky security software such as Kaspersky Anti-Virus and Internet Security. When a malicious file is detected on a computer, it is analyzed by the software and after confirmation as a virus, it is sent to the quarantine folder and saved as KLQ file. This KLQ file grows with passage of time as the Kaspersky keeps adding the virus to it. The malicious viruses are encrypted so that these can’t be executed again.
KLQ File Format - More Information
KLQ files are saved to disc in encrypted format so that these can’t be again used by any other application. These grow in size with passage of time and will occupy space on disc. Therefore, these need to be deleted/cleared after some time in order to avoid occupying large disc space.