To check the credit transaction history, you can check the total consumed credits to date and the current balance of credits. This information is available on the credit page.
To check live credit payment/recharge transaction history, you can visit the credit page and check the recharge history section. For all successful transactions, you can download the invoice from here.
We are also building a section to display per API level transaction and status. This is currently under development and will be available under the usage insights tab.