OK so if can not find it looks as though Ebay will end it as per below

If you enable the out-of-stock option, and your Good 'Til Cancelled listing has a quantity of 0 for the entire 30-day billing period, at the end of that period you may qualify for an insertion fee credit and a credit of any advanced listing upgrade fees applicable to that period. Learn more about receiving insertion fee credits.

If your listing has a quantity of 0 for the entire 30-day billing period for three consecutive 30-day billing periods, we end it.