A 14.1 oz canister of propane lasts for 1.5 to 2 hours of burn time.
If you use the 14.1 oz of propane sparingly then it may last you a few months or so.
I use a 14.1 oz canister of propane with a propane torch to light my wood stove with and I use it daily and it lasts me the whole winter.
Now if I used the propane more then it would not last as long.
But the 14.1 oz of propane does surprisingly last a lot longer than most people would think as well.
The propane in the canister will last quite a long time even when not used.
The propane does not go bad and I've had some propane bottles with propane that had been in them for 10 years and they've worked just fine.
However propane is more costly in the small canisters than it is in a larger tank.