Currently, you can purchase Reddit Premium as a gift for someone by logging in to reddit.com on your computer’s web browser. (Sorry, but you can’t give Reddit Premium as a gift on the Reddit app or old.reddit.com.)
To give Reddit Premium as a gift, you need to purchase Reddit Coins. Once you have Reddit Coins, visit the profile of the person you’d like to purchase a Reddit Premium subscription for and select the More Options link under the Follow or Following button, then click Give Premium.
If you have more questions that aren’t covered in these FAQs, check out r/help. Someone may have had the same question, or you can ask a new one and a Reddit administrator or one of your fellow redditors will help you out.