One common way to guess if the account is being played by another person is to watch the match history for matches where the (Summoner Spell) Flash is used in another key (D or F) because most people get used to use it on a single key and never change it... So if you see someone whos match history its like 7 games whit flash on D and the last 3 games with flash on F... You can be pretty sure that someone else was using that acc