I don't understand why our country or even world does not have this justified already. Many children are being mistreated and abused because some teenagers had a child on accident. I say if you really want to have a kid then you will go the extra mile to be able to have one. The state or country needs to have proof that these people are mentally, physically, and emotionally stable to have and care for a child.
While I understand that the point of having a license in order to be a parent is an attempt to limit/eliminate mistreatment of children by parents, I also do not think it is feasible. Firstly, parenting is a somewhat subjective thing, and there is no 'one' way to correctly be a parent. Yes, most would agree that someone who is not financially or mentally stable should not have children and could therefore 'warrant a license' However, how would this be monitored? Police would have to check for parenting licenses and whatnot and I just don't think it's realistic or worth it. And what would the punishment be for having children without a parenting license?