When Riot Games introduces the Vanguard anti-cheat to League of Legends, you should STOP playing and you should not install the anti-cheat when you get the pop-up. Vanguard is a kernel-level anticheat and these anticheats operate at a privilege level HIGHER THAN YOUR OWN. The anti-cheat can do things that even you can't do, without asking or letting you know. It's like Riot installing a camera in every room of your house and getting a copy of every key inside.
Here is just one example of what they can do: https://www.theregister.com/2013/11/20/esea_gaming_bitcoin_fine/