This is Jennifer from IObit Software. Thanks for your trust in IObit products! If it displays ” not valid license” when you enter the license, please check if the version you use is v6? The license is valid in IObit Malware Fighter v6.
You could download the v6 installer from http://update.iobit.com/dl/cus/imfv6-setup-gmbd.exe or from https://www.iobit.com
Hope all of you enjoy our product! :)