I paid to upgrade from the free version to the home secuirty for up to 3 PCs for one year. Received a licence notification and a receipt, but when I try to upgrade nothing happens using the licence provided?
What avast version are you using 4.8 or 5.0 ?
Presumably you bought version 5.0 Pro license, which comes with a license file and that is no use for 4.8 if you still have that installed ?
How are you trying to upgrade, exactly what are you doing, before the resulting ‘nothing happens’ ?
How to register avast 5 pro on page 7 - 8
http://www.avast.com/documentation/quick-start-guide-pro-en-ww.pdf