How do I keep using Norton after formatting my pc?

Hello there,

I have purchased for Norton 360 and I still have about 70 days until it ends, But my laptop is very slow although I keep fixing it by Norton every time I use it, And I also scan it from time to another…

So, Now I’m thinking to format my pc, Because it seems the only to me to fix it.

My question is: Will I be able to use Norton again after formatting my pc?.. And if the answer is yes, Could you please tell me how?

NOTE: I don’t have the serial number anymore, Neither the CD itself or even it’s cover! I don’t have anything at all and I don’t know much about the world of computers and complicated stuff :confused:
So if you would like to help me, Please use easy words with step by step so I can get it right.

Greetings.