If a player has not played for a long time, their summoner name will be tagged as unused, and another player can claim it when they purchase a summoner name change. The inactivity period before a summoner name becomes claimable depends on the user’s summoner level but ranges between six and 30 months. Do note that inactivity is tracked by playing the games so a person can’t prolong this period by simply logging into the client. RIOT won’t notify you if a name becomes available for security reasons. Account usernames never expire. However, since these names are not visible to other players there is less of a reason to need to change them. If your summoner name was claimed this way, you’ll be prompted to make a new one the next time you log into the game.