Avast! as it updates itself automatically and advises it has done so both verbally and in a pop-up panel (blue). A red box means it was unable to connect to the website (probably because of not being online).
If you register it you extend the period of use from about three months to just over a year, although there are normally new versions every couple of months or so. Just installing gives the basic period length of use.
Make sure, when you register, that you tick the Home Use only box.