You will receive an email receipt confirming your purchase. The email will contain your order number and order information, and a link for contacting Doctor Web's support service regarding questions concerning purchase, payment and refund. If you have not received such an email, please contact Google Play's support service — Doctor Web's support service won't be able to help until your payment has been received.
The list of your paid purchases can be found in Google Wallet. The list of applications that have been paid for and are thus available to you can be found in the My Apps section of your Google account.