I had the same message from Adaware today but I thought it was an invitation to upgrade to an enhanced version (for about $9).
I thought "I'll do that: for $9 it's worth it." When I clicked on the button, it then asked me to pay £14 plus VAT, at which point I closed that screen and updated the free version. $9 is £4.50 as near as makes no difference - I couldn't see what the other £10 that US customers don't pay was going to buy me, so....