What it usually means
Dreams hand you a key when something is closed. The dream is rarely interested in the object itself; it is interested in the gap between you and whatever sits behind the door. A key stands for the means of getting in — a solution you half-suspect, a permission you are waiting for, a part of your own life you have not opened in a long time.
Because a key implies a lock, it also implies that something was deliberately shut. Locks are not accidents. Someone closed that door, and often it was you. So a key dream usually carries a second, quieter question underneath the first: not only how to get in, but why this was closed, and by whom.
Keys are also authority in small domestic form. The person holding the keys is the person allowed inside. Anyone who has been handed the keys to a house, an office or a car knows the weight of that small exchange, and dreams make full use of it.
What changes the meaning
This is where a key dream becomes readable. The same object points in different directions depending on what the dream did with it.
A key in your hand, unused. You hold the means and have not used them. More often a dream of hesitation than of obstacle: the way in exists, and the dream is waiting on you.
Searching for a key you cannot find. The search is the content, not the key. Something is available in principle and out of reach in practice — a sentence you cannot say, a decision you cannot reach, a memory that will not come when called.
A key that does not fit. The sharpest of them. You have a solution and it is the wrong solution: effort applied accurately in the wrong place. This one turns up during stretches of work or of a relationship where the same approach is repeated long after it stopped working.
Being given a key. Access granted by someone else. Notice who gave it — a dream puts a very particular person in that role, and the choice is rarely idle.
Giving a key away. Trust or surrender. Which of the two it was is usually settled not by the act but by the feeling that came with it.
A key taken from you, or one you are hiding. Control over access: who is allowed into your life, and who decides that.
A ring of many keys. Several ways in and no clarity about which. Usually the texture of an overloaded period rather than a message about one particular door.
When it keeps coming back
A symbol that returns night after night is rarely repeating a message. More often it is reporting that a situation has not moved. A recurring key dream tends to accompany a stretch of life in which the same closed thing is still closed — an unmade decision, an unspoken conversation, a part of yourself you keep meaning to return to.
Watch what changes around the key rather than the key itself. If the key stays and the door keeps changing, the subject is access in general. If the door stays and the key keeps changing, the subject is means. And when a recurring key dream stops, something has usually opened; it is worth knowing what.
In Jungian terms
Jung treated symbols as images the psyche makes for itself, not as entries in a fixed code, so there is no sentence that begins "a key always means". What the image offers is a shape: a locked room is a part of the psyche that consciousness has shut out, and the key is whatever would allow contact with it — an insight, an admission, a person, a piece of work.
That is why the figure holding the key carries so much weight in these dreams. A stranger, an elder, a child, an old friend pressing a key into your hand can stand for a part of you that you do not recognise as yours in waking life. Jung's word for that material is the shadow, which does not mean anything evil. It means unlit.
The practical form of the idea is modest. A key dream asks what has been closed off, who closed it, and whether you still want it closed. Sometimes the honest answer to the last one is yes.