How many licenses do I need?

Hi;

In my house, I have

1 desktop pc, 3 laptops, 1 Ipad, 1 Surface Pro, 1 Windows phone, 2 Android phones

and 2 children.

It looks to me that I would need 4 x licenses to run Norton Family across these devices - £120 per year.  

Is this correct?  As it seems ridiculous.