The store has a year to return those books for full credit. (slaw.ca)
But, if you're creating demand and readers are out there looking for your book, then instead of returning books, you should see subsequent orders for MORE books come through! (nonfictionauthorsassociation.com)
How would you like to sell to a customer that needs your content, has virtually unlimited funds, and does not return your books? (ingramspark.com)