If you see the error "invalid data entered", your computer may be connected to the internet via a proxy server. That would block any attempt to activate the license. This is fully described in the User's Guide installed with the software.
Please try manual activation by following these steps...
Step 1 - Temporarily disconnect your computer from the internet
Step 2 - Run GBDeflicker and click Register in the effect's License menu
Step 3 - A URL and Request Number are displayed.
On a computer with an internet connection go to the URL and enter the Request Number and other information.
Step 4 - Fill out the form and click Send
Step 5 - Select the number to the right of the words “Activation Code” and copy the value into the computer’s clipboard.
Step 6 - Go back to the GBDeflicker Activation window
Step 7 - Click the Manual Activation button.
Step 8 - Past the activation code into the form and type in your serial number
Step 9 - Click “Activate Now”