Login to you Epic Games account, navigate to the download page and click Redeem your Epic Games CD Key Button. The game can then be installed in your library and played from your library at any moment you wish.
A 3 out of 10 EP 4 Thank You For Being An Asset key for the Epic Games-Client does not expire and after activation 3 out of 10 EP 4 Thank You For Being An Asset can be downloaded and played forever.