Delta customers with American Express credit cards, take note: The days of unlimited trips to the the Atlanta-based airline's Sky Club lounges are over. Driving the news: Starting this month, Amex cardholders will have a limited number of visits to Sky Club lounges during the calendar year.

The network of 56 clubs covering more than 700,000 square feet provides a place to work, eat, or sleep, all in a modern, luxurious setting. In Boston, the Sky Club features locally inspired seafood and desserts.

American Express imposed limits on how many times Amex Platinum and Delta Reserve cardholders can access the Delta Sky Club. Here's how to track your visits.