Do we only have a window of opportunity to lose weight with a gastric band? I've heard this but it doesn't make sense to me. If so, how long is it? and why would it(the band) stop working after a certain amount of time?

I dont think there is necessarily a window.

However, it is easier to lose weight in the beginning because at a higher weight, your body uses more calories to maintain your body and the weight drops faster.

It is also easier to lose weight in the beginning because motivation is higher and you start with a liquid diet.

I can see that if a person does not follow the program and bandster rules in the beginning after banding and has minimal or no success at banding once they reach restriction . . . then chances of future success are diminished.

You have to be committed to the lifestyle. If you are committed, then I think you can find success at banding during any point in the journey whether it is in the first 6 months or 10 years down the road.