Due to changes in the program core between 6.X to 7.X a direct upgrade is not possible. Please review and follow the information provided in KB 302431 and follow the instructions provided to complete the upgrade.
This new release of Syslog NG Premium Edition 7.x requires a new license key. Please obtain the new key before installing the new release. To obtain a new key, please refer to the License Key Upgrade page: License Key Upgrade.