Use the money tab to see a record of credit card charges on your account. USPS charges are charged via your credit card on file.
Then, you can click on any of the entries that match on or around the date and amount that matches your credit card. Keep in mind, the date may be off by a day or so if the charge on the credit card is recorded late in the day/weekend.
Then, you can view or download a PDF of the charge detail. You can search the unique number of the item over on the track tab to get more info. In this example, search for item 517663 in the track tab.
You may need to login to another portal to see subscription fees. You can login with your registered ShipLeap email on file here: https://billing.stripe.com/p/login/7sI5mK87B8or5LGfYY
Please send an email to support@shipleap.com if you don't remember which what email is registered to your account.