How Does Amex NPSL Work?

[CalAlumnus13]

I know the basics: NPSL doesn't mean unlimited spending, and Amex can deny a charge if it exceeds what they think I'm able to pay, based on what they know about my income, credit, and past spending.

My question is this: Could my PRG have a relatively low "credit limit" beyond which I could not make any purchases, even one that's relatively small ($50-$100) and consistent with my past purchases? 

Basically, I'm worried about using the PRG for dining, and getting a meal declined unexpectedly in front of friends or family. Could this realistically happen, assuming I haven't already spent x times as much as I normally do in a month?

(I'm aware of the Check Spending Ability tool, but that seems to relate more to a single large purchase than to an overall limit.)

[Josh2942]

They wont drop your internal limit down just because you dont use it. I never use my NPSL cards but I have an internal limit of 4k all the time. You can also call AmEx and they will tell you your internal limit.