SAN FRANCISCO (AP) — MoviePass, a startup that lets customers watch a movie a day at theaters for just $10 a month, is limiting new customers to just four movies a month.

The move comes as the sustainability of MoviePass' business model comes into question. Because MoviePass is paying most theaters the full price of the ticket, the service loses money with just one or two movies in a month.

MoviePass regularly changes its promotions and rates, and it's not clear whether the one-movie-a-day deal will return. It appears customers who have already signed up under the old plans aren't affected, but it's not known whether they would be able to renew under the more generous terms. MoviePass would say only that it is "continually testing various promotions."