A year ago, Apple settled a giant class-action lawsuit (details below). The result was that millions of Americans got free credits in their accounts at Amazon, Barnes & Noble, or other e-book retailers. If you're an American who is reading this article and you've bought e-books in the past, there's a very good chance that you were included.

The catch? If they haven't been used already, these credits will expire this Saturday at midnight Pacific time.

Below you'll find: (a) how to check your balance, (b) background on this whole affair, and (c) why you should stop to think whether you're still using the email address you used during the first half of this decade. In my case, logging in on a whim with an old email address more than doubled my credit. (But even having found it, I then promptly forgot all about the credit again for nearly a full year, until just before it expired.)

How to check your balance

Maybe you already knew that you had a credit, and you've already spent it. That's probably the case for a majority of people at this late date. But if you do want to check your Amazon account quickly, here's what to do.

  1. Go to this page on Amazon. You'll find a page entitled "Information for 2016 Apple eBooks Antitrust Settlement." If you're not signed in already, you'll be prompted to do so.
  2. If you were awarded credits, you'll see a display that provides your "Total Credit," along with "Unused Credit" and "Expiry Date." If you've made purchases during the past year, of course, you might well have spent the credit. The Expiry Date should be June 24, 2017, in almost all cases.
  3. If you were often using another email address between 2010 and 2012, however, you might try logging in with that one too. Amazon presumably wants you to use these credits--it's a purchase that Apple is paying for, after all--but it can't necessarily tie accounts together, and let you know if there's money waiting for you in an account you don't often use.

Will this apply to everyone? No, but I mention the part about the second email address because adding that step brought my total credit from $17.92 to $39.09 in total.

For reasons you'll see in the next section, while Amazon is likely the most important retailer to check, it's possible you could have a credit with another retailer who sold e-books during the first half of this decade. I couldn't find a similar one-stop page on Barnes & Noble, for example, but this page gives you more information on how it calculated credits, and you should simply be able to log into your account to see if you still have money waiting for you.

Background on the whole case

All of this goes back to 2009. Amazon's Kindle had 90 percent of the e-book market, and Apple was trying to break in. Steve Jobs was still CEO, and he sent executives to try to work out a deal with some of the biggest New York publishers.

Basically, Apple offered to let publishers set their own prices on Apple's platform, and agreed to take only a 30 percent cut. But Apple also required that the publishers agree not to sell to any rival (like say, Amazon or Barnes & Noble) for less. Overnight, some e-books that had been selling for $9.99 on Amazon rose to $12.99 or $14.99.

The U.S. Department of Justice and some state attorney generals got involved, and there was a big lawsuit. Ultimately, Apple agreed to pay $400 million in a settlement to "millions" of people who bought e-books at inflated prices, in the form of credits at Amazon and other retailers. If you bought any big, best-selling e-book between the middle of 2010 and 2012, you were probably part of the lawsuit.

The extra tip

A year ago, I wrote about this settlement when it first came out, and people started to get their credits. But I also mentioned that I'd realized that I had a second email account with Amazon back at the start of this decade.

Hence my zealotry on this idea; when I logged in under the second (older) email, I had another $21.17 waiting for me.

How's this for irony, though? Despite all that, I actually forgot about the second email address and the second credit until this past weekend, when Amazon helpfully sent me a message reminding me that it was there, and that it was going to expire soon.

That leads me to one more little trick for you: I'd been thinking about getting an Amazon Echo, so I decided to use the second, forgotten credit toward it. But then I realized that this older account with the unused credit wasn't signed up with Amazon Prime. Talk about a First World problem, but this meant if I wanted free shipping, my new Echo wouldn't arrive for about five days.

I went down a bit of a rabbit hole trying to research how to merge two Amazon accounts, or at least transfer a credit from one account to another, so let me save you the trouble, in case you ever need to do this. There's no way to accomplish it online, but if you call Amazon Customer Service at 1-888-280-4331, they can do it for you.

For security, you'll need to have both email addresses, along with the first names listed on each account, and at least one address associated with it. It took a little over 10 minutes in total.