Hi Sandy,
I'm afraid there are no action commands present in TAB yet for changing the lightsource status of an object.
In other words if you assign a lightsource attribute to an object in the Object Editor then there is not a way to turn that off during the game.
However, this is something new I can think about implementing for the next release...
One thing you can do is to remove the "lantern" from the game when it is used up by using an action such as 'destroyX' or 'objlocX=0'
Alternatively you could create 2 lantern objects.
For instance a 'lit lantern' and an 'unlit lantern' and use the procedure similar to the "torch" example in the below forum topic.
This requires a bit of extra coding though so please read it carefully.
https://adventure.forumotion.com/general-forum-f1/darkness-and-lightsource-t21.htmRegards,
catventure.