Upon completing a payment in the Steam environment, the receipt will be sent to the email address linked to your Steam account. Please check that receipt. However, if the receipt was not issued to your linked email address, please check it through the method below.
[How to Check Receipts on the Steam Client]
1. Steam Client > Account Details
2. View purchase history
You can view your receipt by following these steps and selecting the payment item from your 'Purchase History'.