If Nero does not accept your serial number, do the following:
Go to the "Nero Control Center" and check the installed products under "Serial number".
Make sure you have the correct version of Nero installed on your system. Click Update in the Nero Control Center to make sure you have the latest version installed.
The Nero Control Center gives you the option to verify that you have entered the correct serial number. If necessary, enter it again to avoid typos. Please note that you cannot install Nero 2017 products with serial numbers before.
If you are using a trial version of Nero 2017 and wish to purchase the product, simply enter the serial number you purchased at the time of purchase into the Control Center. 'And the complete product has been activated