Google play store actually does a authorization transaction of around 1$ immediately after you pay for some apps or in-app products. This is done to check the validity of the card. The transaction is usually reversed in few hours.
One star and a very bad review: it hurts badly
One user of my app classify gave me a one star rating stating that he has paid for the pro feature and not getting the promised features.
The transaction was not actually complete from his side and only the authorization transaction message was delivered to him.
I had to explain step by step that it was google's normal system. Finally he agreed and upgraded to pro from different card and then removed one star and added five stars.
That made me to share this useful info to both app users and developers. This is crucial as such reviews can have a negative impact on other buyers. And also developers has to understand this process to better explain the customers that the amount will be reversed.
Useful info that I collected about this transaction
Even iTunes and App store does such transactions
Authorizations are transaction requests that occur between Google’s billing system and your bank's billing system in order to ensure that the card is valid and that the necessary funds are available in your account before the order can be successfully charged. Authorizations take place every time you update your credit/debit card or you place an order with Google Wallet.
Please note that these authorizations might remain visible in your account between 1-14 business days, depending on your card-issuing bank. However, keep in mind they are authorization requests only, not actual charges. We recommend that you contact your bank to check on when the authorization request will be removed.
Finally, you may notice a $1.00 transaction from Google on your bank statement. This also is only an authorization request and be sure you will not actually be charged.