MoviePass, an app that lets you pay a monthly fee to watch a movie a day in theaters, is launching publicly starting today.

Think of it as Netflix for movies still playing in theaters.

The service costs about $30 per month, depending on your location, and lets you reserve tickets from your smartphone and load them on a pre-paid card. You then swipe your card at the theater's kiosk to receive your ticket. The card has built-in geo-location so it can confirm you're actually at the theater.

The app is only on iPhone right now, but an Android version will launch next month.

We spoke with MoviePass' CEO and co-founder, Stacy Spikes, and he explained how the service works and lessons learned from the closed beta testing.

He said MoviePass' goal is to remove the friction of movie-going, just like Netflix, Hulu, iTunes, and other streaming services make it easy to watch stuff at home.

Users sign up for MoviePass at www.moviepass.com. The service is invitation-only right now, but once you've been given access, you'll receive a special geo-located reloadable debit card. The debit card will work at all theaters that accept credit cards. It's the same process you use when you purchase movie tickets online and use your credit card to redeem them.

But there's a catch: the MoviePass card will only work when its near your cell phone and the theater. That helps prevent people from abusing the service.

On the business side of things, Spikes said it took a lot of work to convince movie studios and theaters they'd make money. Theaters are still paid full price for the ticket, even if the user sees a movie every day. MoviePass has cash from its investors like AOL Ventures, plus it makes money from other services it sells. And by making it easy for people to go to the movies, there's more opportunity for theaters to make money from concessions.