How does keys work?

1. Key fragments only drop on wins, in modes that give Champion Mastery
2. They are random, meaning you won't get one every win
3. The drop rate decreases for every fragment you earn

• This rate resets roughly every 30 days after your first fragment

4. If you play enough you can earn up to 12 fragments (4 keys) each month
5. Larger premade groups give you a higher drop chance
6. If you get a behavioral punishment you'll be ineligible for loot for a while

Read here for more info on the Hextech Loot system; http://boards.eune.leagueoflegends.com/en/c/champions-gameplay-en/KZnWzcGK-hextech-crafting-and-mastery-frequently-asked-questions