StarPass is like any other form of non cash payment. It may or may not be usable at the location you are at. It doesn't matter the credit limit on my visa card if no one at the craft fair has a payment card reader. I probably can't buy illegal weapons with my visa card regardless of where I am.
A Starpass is probably not the best use of a 250k windfall during play, just like few people are going to actually pay to join TAS during the course of a campaign. But as a mustering out benefit, both are pretty good deals.