Please browse to License Server folder. If you have selected a default installation path, then browse to: C:\Program Files\Transoft Solutions\License Server
Right click on the License Server folder, select Properties and click on the Security tab. Please check if the SYSTEM is on the list and that it has Full Control. If the SYSTEM is not on the list or does not have Full Control, please add it and change permissions accordingly to allow Full Control for the SYSTEM.
After that, reinstall AviPLAN.