Norton 360 and Norton internet security

2 questions:

 

just got a new computer - replacing the old one - no longer in use. Tried to install my 360 and NIS subscriptions that have been paid for, but being told too many installations for product code. All I'm trying to do is protect my one computer - don';t want to buy another subscription...help?

 

second question: do I need both subscriptions (260 and NIS) I think I might have purchased both in error and now I'll keep getting renewwal billings for both