Under Armour Inc. employees received an email earlier this year that upended a longstanding company practice: They could no longer charge visits to strip clubs on their corporate cards.

Over the years, executives and employees of the sports-apparel company, including Chairman and Chief Executive Kevin Plank, went with athletes or co-workers to strip clubs after some corporate and sporting events, and the company often paid for the visits of many attendees, people familiar with the matter said.

Strip-club...