I used Google Checkout API for getting subscriptions reports every half an hour. https://checkout.google.com/api/checkout/v2/reports/Merchant/ (https://developers.google.com/checkout/developer/Google_Checkout_XML_API_Order_Report_API)
Our company have ours support team which provides help for users of application. My script downloaded last purchases every half an hour and stored in DB (time,serialnumber,email). After that support was getting access to this information through our web-interface (thus, we did not give an access (login,pass) for a main Checkout account).
Now Google Checkout was shut down and I don't understand how to do it at Google Wallet. Does anyone now can it provide this functionality or not?