How old does a debt have to be in order to not pay it. Columbia house after 9 years just now want me to pay them. I don't even remember this anymore.

A valid debt NEVER expires. If you signed a contract to pay for services, and you received products or services you never paid for them then you have an obligation to pay and they can dun you for that money.

However, there is a statute of limitations on how long they have to use the legal system to collect on the debt. The SOL will vary from state to state and the type of debt. But if there has been no activity for 9 years the SOL has probably expired.