He hasn't been in prison. He's been in jail. He is not convicted yet, so his tugboat is still alive. It is still being deposited in his account every month. If he is let out on time served, plus up to 29 days of further time in jail, his tugboat will not stop.
If he receives a total sentence that is time served plus 30 days-1 year, he will probably still spend the rest of it in jail. The tugboat will stop after 30 days, but once he is released he will be able to send in a simple form to reactivate it.
If he receives more than a year after time served, he will most likely go to actual prison. His tugboat will still stop after 30 days. When he is finally released, his tugboat will not restart -- he will have to REAPPLY for it. This is a more difficult and involved process, but would still probably be successful if he had someone helping him with the paperwork.