This file will explain what all the files are for
ipData.yml:
    IP addresses are saved in this file in order, from oldest to newest.
    This is used to track player alts and to prevent users from using the username
    of another player (this is especially important for offline mode/cracked servers)

loginData.yml:
    Login history is saved in this file in order from oldest to newest.
    This is used to help users determine if someone logged into their account.
    This is also used to help detect player alts and to get when someone logged in as another player.

cache.yml:
    This file is used to store cached data and flagged players.
    Do not delete or edit this file. If you do, run /flagplayers to rebuild the cache.