The settlement is not for people who purchased books from Apple’s iBooks store: they’re included, but the price-fixing settlement includes people who purchased any e-book from Hachette, HarperCollins, Macmillan, Penguin Group USA, and Simon & Schuster. Thanks to the vast array of imprints each publisher puts out, those could be under any of dozens of names: you can find a full list of imprints that would have been included in the suit in this PDF document.
$400 million of Apple’s settlement is earmarked for refunds to e-book customers. Appleinsider reports that you can expect between $6.05 and $6.54 for each bestseller purchased during the key period, and between $1.39 and $1.50 for each non-bestseller. You will not receive settlement funds for books that you downloaded for free, rented, or received as gifts. The books had to be purchased between April 1, 2010 and May 31, 2012.
However, the easiest way to know whether you’ll be receiving money from Apple is if you have already received money from your e-book platform(s) of choice. Google required affected users to file claim forms by October 31, 2014, and Sony issued payments automatically, but as paper checks. The other major e-book platforms automatically issued credits to users, and will do the same again once the Apple settlement is finalized.
If you need to update your contact information with the e-book stores, the state attorneys general behind the antitrust suit can direct you to the places where you should update your information for each store.