Norton Internet Security™ 4 for Two Macs

I have a few Questions:

 

1)   Can I use NIS4 on two computers? 

2)   If I can't, must I pay for two  . . . or , at a lesser price, use same software for an additional fee?

3)   What happens after the 1-year period ends?

4)   Must I renew it?  If I don't what happens then?

 

Thanks to all.