A trial reset is a third-party software utility (often called a "KRT" or Kaspersky Reset Tool) designed to clear the registry keys and hidden system files that track the duration of a software trial. By removing these traces, the software perceives the installation as "new," allowing the user to initiate another 30-day trial period indefinitely.
To continue using the full suite of "Total Security" features, you can purchase a renewal code. According to Kaspersky Support
This article revisits 2021 specifically, explaining the methods that were circulating, why Kaspersky patched them, and what alternatives you have today.