I worked for sams club for 2 years while I was in college. And when I first started I was a cashier... If you make it in the door you will most likely be ok. 95% of people won't give you any trouble for using someone else's membership. Because 1: They aren't paid well enough to care, and also I and many others aren't that big of dicks to turn you away after you have already spent an hour or more of you're time picking out your items and putting them on the conveyor belt. There's no way I could turn someone away at that point. Especially with business memberships as well, since there is a clause where other employees of the business who might not be pictured on the card are authorized to use it. The only time I would ever say anything was when it was obviously not the customer's card and it was a credit membership AND THEY WERE TRYING TO USE THAT PERSON'S SAM'S CREDIT CARD AS THEIR METHOD OF PAYMENT. Because I believe that could mean possible legal ramifications for me personally if I knowingly allowed someone to use someone else's credit card. That is the only time I and most employees would ever ask any questions.