All of them. Neville Longbottom could only ever remember the first password used by the Gryffindor common room in his fifth year because it was the name of his plant, Mimbulus Mimbletonia.
In Harry Potter and the Philosopher's Stone he notably forgot the password "pigs snout" and was sleeping on the stairs after being locked out overnight. That is until Harry, Ron and Hermione found him on their way to a Midnight Duel.
In Harry Potter and the Prisoner of Azkaban, Neville wrote the weeks passwords down and then lost the piece of paper, which was actually stolen by Crookshanks and given to Sirius Black. After Sirius used it to enter the common room, McGonagall banned anybody from giving Neville the password and he would have to wait until somebody let him inside.
Neville forgot the password to the common room.
No, Neville Longbottom is not single.
She went with Neville Longbottom
Harry Potter told Neville Longbottom that Nagini had to die so Neville Longbottom decapitated her.
Neville Longbottom beheaded Nagini, the snake.
Neville Longbottom forgets most of the passwords for the Gryffindor dormitory, including pig snout which was the first password.
Neville forgot the password to the common room.
No, Neville Longbottom is not single.
It is unknown if Neville Longbottom had any children.
Neville Longbottom became the Herbology teacher at Hogwarts.
She went with Neville Longbottom
Neville Longbottom is a/an Professor of Herbology at Hogwarts School of Witchcraft and Wizardry
Harry Potter told Neville Longbottom that Nagini had to die so Neville Longbottom decapitated her.
Neville Longbottom beheaded Nagini, the snake.
Mimbulus MimbletoniaA.K.A Neville Longbottom's plant thingie (told on Hogwarts Express)
Neville Longbottom? Augusta
It is unknown.