If you have the bogo credit coming in on a line and you paid off that device, as long as you don't upgrade that line you will continue to get the bogo credit until the final installment was set. Example you have line A, you added line B for bogo, the way it works every month you get a credit to equal the installment amount on line B for it to be essentially bogo canceling out what you owe on it. Let's say the normal installment amount is $25, every month they give you the credit of $25 to counteract it. Let's say on line B you owed $250 left, equaling 10 months. You accidentally pay off the remaining balance making it $0. As long as you don't upgrade the line the terms are still in effect, so you'll continue to receive the $25 a month for the next 10 months. - Used to do customer care for AT&T wireless, it's usually the same everywhere.