Child support ends when the court order says it ends. For most states in the US, that would be when the child attains the age of majority (18-21 years old). This is assuming, of course, that your parents were divorced in the US, since this site deals with US law only.
I understand that. I doubt the vendor knows the age of the account holder. I was merely giving a legitimate reason why there might be new accounts set up at a given location under another 'first name different, last name the same'.
Actually, that is not entirely true. While a judge will listen to a 14 year old, best interests of the child now come into play. This is to stop parents from bribing their 14 year old children into living with them.
OP could have purchased a new PC and had problems within hours as well. I delivered and set up a PC and had to go out the next day because it wasn't booting. The CPU fan wasn't fastened on. This was just out of the box brand-new. But, there was a solution - HP replaced that PC.