Can a new Avast license be added to extend a current one?

I just bought a two year license for Avast Ultimate. I already have Avast Ultimate on the PC with about six months remaining on the current license. Is there a way to add the new license to the current one to extend the time, or should I just wait until the old license runs out? TIA

 

So in AVG all you have to do is add the new license key to your account and the portal will ask you to extend. I assume the system is the same for Avast. However, if this doesn't work, customer care will sort it out for you.

 

Thanks, I'll have a look at that