Sure the game is free to play, but you spend on the in-game items.
Lets take a look back at your spending on the game LOL.
They now officially have a section dedicated to do showing you money spent in the game.
You Must KnowThe amount reflected applies to the current region on the account.
It will not include the spending outside the region currently associated with your account.
Stay away from all the third-party sites promising you to inform you about themoney wasted on lol.
They may have other nefarious motives and can result in losing ownership of your account.
source: www.techworm.net