I suggest you to uninstall the application using Revo Uninstaller. Even if it can't uninstall the application normally, it will force it to uninstall by wiping out all traces of its presence from the system. When you will be asked for the password, click Cancel and follow the instructions.
Next, try running AdwCleaner 2-3 times in a row to make sure that there are no leftover rogue registry keys that can contain your Admin information.
After that, download again the antivirus from the official web page and install it using the serial number received when you purchased the program.