Final answer:
In the context of the passage, the custodian of all magazine keys is not clearly specified.
Step-by-step explanation:
In the context of the passage you provided, it appears that the custodian of all magazine keys is not clearly specified. However, the passage mentions that several keys to the narrator's door are held by different individuals. The keys are kept by a woman residing in the attic, Turkey for convenience, and the narrator sometimes carries one in their own pocket. The fourth key's holder is unknown.