I was on a flight (last year) due to depart at 22.55 hrs - this was delayed for about an hour and the lounge was open until we departed - it seemed as if everything was still out and operational when we left.
One of the lounge staff did mention that Ukrainian Airlines (?) used the lounge as well - don't know if they still do- and they were open until the last flight left which on that day was a delayed Ukrainian.