Do Facebook Requests Expire?by Nick Peers
On Facebook, you have the option to make your profile private and allow only friends or specific people to view your posts, photos and information. People who want to view your profile and posts and interact with you must send you friend requests. You have the option of accepting or ignoring these requests. Facebook doesn't notify the user when you ignore his request. However, he can send another friend request as soon as you ignore the first one.
Facebook Requests Facts
Facebook requests do not expire. You can accept a friend request or ignore it. You also have the option to hide the request and deal with it later. If you don't take action, the request remains active indefinitely. However, the user may cancel his request if you do not accept or ignore it. If the user cancels it, the request disappears from the Friend Requests page; it does not expire automatically.