The free version of Norton antivirus is very draining on your system’s performance. It tends to control your computer more than it should, and it is full of ads. It is also slow. The paid version, while offering more features, is not necessary and still suffers the disadvantages, minus the part about ads.
I recommend you do not use Norton. My personal recommendation is that if you are running Windows 10, you use the built-in Windows Defender antivirus, coupled with the free version of Malwarebytes.
If you are using Windows 7 or Windows 8, which does not include Windows Defender, I suggest you use the Kaspersky. It is very light, and the ads can be turned off in settings.