The answer is subjective, as is so much in parenting. Since there is no definitive medical advice on when you should quit, it is important to consider your own family's circumstances. But here are some points that may help you make a better decision.
To begin, it’s recommended by most professionals that you discontinue using a baby monitor once your child is 4 years old. This is because, by that time, your child learns they’re being watched. Secondly, they've become used to sleeping in their bed.