Spoiler warning: Spoilers for the complete television series, including Season 3.
The Lockes throw the magical keys into the portal, sealing the connection after Gideon’s defeat. Locke & Key ends with the family choosing to give up the source of its extraordinary experiences rather than preserve the danger attached to them.
Why doesn’t defeating Gideon close the story?
When he falls into the portal carrying two keys, the opening shrinks. Tyler recognizes the connection, and the family understands that returning all the keys can close it.
The villain’s defeat is therefore an opportunity to address the source of the threat, not proof the threat can never recur. Keeping their powers would also mean keeping the conditions through which further harm can enter.
That choice has become harder to avoid after possession, deaths and repeated attacks. Enjoying some uses of the keys no longer makes the other consequences separable from them.
Why visit Rendell first?
The Timeshift Key lets the family spend one final moment with their father and husband before surrendering the magic. Saying goodbye gives the decision a personal cost beyond losing useful abilities.
It also distinguishes remembering Rendell from retaining permanent access to him. The visit can matter without becoming a reason to hold the dangerous connection open indefinitely.
The family then returns to the present and completes the sacrifice. Their ordinary future cannot be indefinitely postponed for another reunion.
Is this how the comics end?
No. The showrunners explicitly identify the portal and surrender of the keys as part of the television adaptation’s own conclusion. Gideon is not the same closing antagonist in the source material.
Readers should therefore not use the series finale as a factual summary of the graphic novels, or import comic events to undo its choice.
For the television family, the resolution changes what makes Keyhouse a home. It can remain a place of connection without giving everyone a supernatural role. The loss of magic is meaningful because the people who choose it have used and loved it, then decided their relationships must survive without requiring its return.
Sources: official ending breakdown.