Please add a copyright page. Open your book with an ebook editor and add a new page at the beginning.
Our stores prefer books with copyright pages in them: this is for your protection.
If you are an independent author without a coauthor, just write your name and the year of publication on an empty page like this:
Your Name © 2017
Copyright by Your Name, 2017
Read here how to add a copyright page using an ebook editor.