Quote from tristancliffe :

You don't need it for LFS, but if you were buying something solid (like a CD) it tells them where to post it to (the bill is the invoice, so the billing address is where the invoice, or proof of payment, is posted).

Hope this helps.

so i just lave it blank? or type my adress?

hello im new here.
im buying my self an S2lisens but what is billing address? im from norway so i dont know that that is..

thanks for qucik replays