<code>{ "success": true,
                    "uses": 3,
                    "purchase": {
                        "id": "OmyG5dPleDsByKGHsneuDQ==",
                        "product_name": "licenses demo product",
                        "created_at": "2014-04-05T00:21:56Z",
                        "full_name": "Maxwell Elliott",
                        "variants": "",
                        "refunded": false, # purchase was refunded, non-subscription product only
                        "chargebacked": false, # purchase was refunded, non-subscription product only
                        "subscription_cancelled_at": null, # subscription was cancelled, subscription product only
                        "subscription_failed_at": null, # we were unable to charge the subscriber's card
                        "custom_fields": [],
                        "email": "maxwell@gumroad.com" }
             }</code>

//taken from https://help.gumroad.com/11165-Digging-Deeper/license-keys#verifying-a-license-key-in-your-application