You were only eligible to receive credit if you had a U.S. billing address and purchased a Kindle book between April 1, 2010, and May 21, 2012, published by one of five major U.S. publishers: Hachette, HarperCollins, Macmillan, Penguin and Simon & Schuster.
The case, which was settled Nov. 21, 2014, addressed the question of whether Apple and the five listed publishers conspired to fix and raise the retail prices of eBooks.
"Under the settlements, Apple provided funds for credits that were applied directly to Amazon accounts of eligible customers in June 2016," Amazon explains. "These credits expired in June 2017. Customers who redeemed credits from the June 2016 distribution received additional credits in October 2017."