Have an email account that is growing cobwebs on it, because you haven't used it in so long (I've got at least three)? How about an email account in which you rarely if ever check the inbox?
If you answered "yes" to either one or both of those, you might want to check it/them if you don't get a message from Google Play in the account that you regularly use.
I just got in my inbox (and not in my primary email account) this offer from Google Play:
SEE WHAT'S NEW ON GOOGLE PLAY BOOKS
$5 CREDIT FOR YOU
Here's your $5 credit to use toward any Ebook over $5. Kick back and relax with a new Ebook on Google Play.
Claim your offer below and your credit will be applied at checkout.*
CLAIM YOUR OFFER
This offer is only valid for [me@noneofyourbusiness.com].
Forwarded recipients are not eligible for the offer in this email.
Note that it seems to be targeted to only certain people (as per usual, it seems).
I didn't see any ebook deals on
Google Play's homepage. Sorry. There is a deal to get 99 cent rental deals on
The Karate Kid Collection movies. You know, I never did get to watch all of those in the 80's . . . .
Best wishes getting the $5 credit deal on ebooks.