I’m running the latest version of Avast free. The update expiry date is 1/2/2010 and I’m just wondering if Avast contact people before the expiry date or it’s up to me to renew
They don’t contact you as such, but 21 days before the update expiration days, you would normally get an update renewal pop-up notice, this also gives options to upgrade to the Pro version if you wish to upgrade rather than just update.
Hi walesbug,
Basically this is the home license expiration date. This means that around this date you will have to renew it (for free)
About 21 days before this you will be reminded about it by avast!
What you do when you are notified is go to this link:
http://www.avast.com/eng/home-registration.php
and click on:
‘My registration key has expired, I need a new one’
You will then be asked to fill out a registration form and then be sent an email with the key, when you do.
You can then input this into avast!
Or, like DavdR says, you may be inclined to upgrade to avast! Pro, which you will find out about when you click the update notification box 
-Scott-