The offers are generally for specific options.

You don’t say if you have avast Pro or the Avast Internet Security, product ?
The AIS product offers the best deals on a 3PC license.

I don’t know if you renew in the normal way when your license comes up for renewal you get a renewal discount. You could contact sales (at) avast (dot) com and ask.

I don’t know if there is an option for 1PC for three years for the same price.