You can generate your license key from your order details page. First, go to your User Dashboard >> Purchases tab. Then click the Order Details button to see order details. There is a key button under the License column ( indicated in the following screenshot ), click it to generate your license key for the current order.
For any technical issue, if you are already using pro version please post in pro forum and free version users please post in free forum. Otherwise, if you have any pre-sale or order related query please contact live chat support team. For technical support.