Since last Tuesday, Apple has given away free downloads of the new U2 album Songs of Innocence to well over 500 million iTunes customers.

It’s worth asking why Apple is doing that. Are they feeling sentimental and this is their version of a big group hug? Are they die-hard U2 fans who can’t bear the thought that the music not be shared? Or are there other forces at play?

If there’s one thing we know about Apple, it’s that they are masters of strategy. And this free download is most definitely a masterful one. By basically giving away the U2 album for free, Apple is encouraging—in a very non-salesy way—a huge swarm of people to get an Apple ID.

By doing so, they gain enough mass for the Apple Pay service to work. It’s a win-win.

Consumers get something for free and Apple gets to build their subscriber database. Granted, it’s an expensive strategy on Apple’s part—who knows how much they gave U2 for the licensing rights. But consider the win for Apple if they eventually dominate the electronic payment business.

Apple is the mega-giant it is because of this kind of thinking. Obviously most firms can’t afford to deliver this volume of free value to customers, but in this digital era there are unlimited opportunities for companies of all sizes to provide “freebies” that would yield a high return.

Want to be like Apple? The first step is knowing your customer base as well as Apple knows theirs. Then you work out what they want, what they’ll respond to and how you’re going to deliver your “U2 album” for free.