I know a guy that left when I started 2 years ago and he walked in the other day and still has it. It all depends on if your account manager notifys Consessions. In his case, he slipped under the radar because of 2 things.
Our account manager doesnt even remember the current date 1/2 the time and 2) we keep growing so I dont think she ever noticed that he isnt with us anymore.
In your case, if the whole retailer shut down and your account manager gives a whoot, then you might lose it but you defently want to make sure you SWITCH to a CONSUMER line because my understanding is that If employee consessions doesnt switch it to a consumer and it gets reported that the Agent is closed, you lose your number and account history. Hence why you cant port an Agent line out, you have to switch to consumer price plan in order to do it.
Hope some of this help you out.