So what does this mean if you're a League player with your eye on that sweet new skin for your favorite champ? Nothing, actually - skins sold through the League of Legends client will still work just fine.
The new policy affects codes that are printed onto cards and given out at events such as PAX, Gamescom and Anime Expo, and only those created before April of this year. These skins, due to their limited availability, are sometimes considered rare, and thus have been sold through third-party sites at a hefty markup. Forbes wrote on the game's forums that Riot found one skin selling for more than $1,000.
If you find yourself stuck with a legitimate skin code that you haven't yet redeemed, you have until July 23 to submit a ticket to League of Legends customer support with info verifying authenticity. Visit the skin code FAQ page to learn more.