The matchhistory command which will allow you to browse the match history of League of Legends accounts and view basic statistics like gamemode, champion and KDA. This feature incorporates a new experimental AI based feature that summarizes your game in one line. You can select a game to show more details about the game like CS, ranks and killparticipation.
None - every user on a server can use this command (as long as not further restricted by permission)
For players which are registered on your server you can simply mention them: /stats matchhistory @DiscordUser
For all other players fill in their region, gamename and tag (Riot ID): /stats matchhistory region gamename tag