When should I renew my subscription to NAV2010?

When should I renew my subscription to NAV2010?

 

I have 12 days left before my subscription runs out.  If I renew today, what happens to the 12 days?  Are they lost or are they added on to the 365 days?

 

Should I wait until my subscription runs out or renew on the very last day?

 

Kimmy