As it says in the topic title I’m wondering how long its been tracking because I’m pretty sure some of my stats aren’t right. I’ve been playing for a few months so far, let me know if more info is needed. Thank you in advance to any responses. 
Hi @Li6ra,
We use your match history to calculate your lifetime stats. However, we have access to recent matches only, which is why your real lifetime stats might be totally different.
Most probably, we have been tracking your stats since you singed up with Riot ID on our website.