A key in a dream is often associated with the unlocking of something – your gaining access to something that was previously unavailable to you. This could be a memory or a feeling that you have been repressing, a talent that you did not realize that you had, or a goal that you did not think you would be able to realize.
On the other hand, a key can be used to lock something, so a key in a dream can represent shutting something away, such as a situation you do not want to deal with or an emotion or memory that you do not want to face.
A key in a dream can represent a solution to a problem.
Dreaming that you are holding a bunch of keys can mean that you need to be open to new ways of thinking and new experiences.