'to last' is not used to mean that something is happening, it is used to say how long it will continue.
The meeting lasted one hour only, but it seemed to be an eternity.
They're triumphing now, but it won't last.
'to go on' means it continues.
The meeting went on and on for hours. What a drag!
The CEO hung up and the meeting went on.
It was 20:00 and the meeting was still going on.
'to be underway' means it has started but it is not finished.
The negociation is underway.