We ran an Event Guest List report and noticed in the "Number of Guests" column, it says 1 (pending). We later ran this report again and we noticed that the record is now gone.
When a user is in the process of purchasing tickets, they are put in to a "pending" status for 30 minutes until completion, so that no one else can buy them. If the user does not purchase them, then the transaction is cancelled. Those who are pending should disappear 30 minutes after the time of execution. This process effectively reserves their ticket while they complete the purchase.