Unfortunately, this is not available to anyone who received free Discord Nitro from Epic Games in prior instances. However, you may share the code with others as a 'gift.'
Discord Nitro enhances your Discord voice, video, and text chat with a range of awesome perks. Nitro offers animated avatars and a custom tag, 2 Server Boosts and a 30% off extra Boosts, the ability to collect and make your own emojis, profile badges to rep your support, bigger uploads (we’re talking 100MB here!), and to top it all off, you’ll get hi-res video, screen share, and Go Live streaming.