NIS License Question

HI

 

I have 2 separate subscriptions covering 3 PCs each, desktops, laptops etc at home ... one just renewed (Feb 2014) and one is due to renew in June 2014. Ideally I'd like to combine them into and add at least one more i.e. 7 PCs. Checking the Norton site I see that there's a 5 user pack and a 10 user pack available. However - the way I'm reading it, financially they don't add up. Also, if I login to MyNorton I can buy a key ... but when I select that option, it prompts me with a key for another 3 PCs, at a higher price than my normal subscription

 

Am I missing something ?

 

thanks,

Duncan