his/her key
Tom no pudo encontrar su llave por ningún lado.
Tom couldn't find his key anywhere.
Tiene el Sr. Harry Potter su llave?
Does Mr. Harry Potter have his key?
— Harry Potter y la piedra filosofal (2001)
We need your key.
Tom parece haber perdido su llave.
Tom seems to have lost his key.
Tom tenía miedo de haber perdido su llave.
Tom was afraid he had lost his key.
Encontró su llave y abrió la puerta.
He found his key and opened the door.