The problem is this is a relatively new product so not many people on the forums know much about it, so most people would be unable to answer it.
My best guess would be that you should uninstall it as:
I don’t know if there is a means of transferring/changing the license number.
the license number is associated with your version of Home Pro Edition and it may look a little strange it cropping up on updates elsewhere. I don’t know what copy protection/anti-piracy measures might be in place.
you don’t know how long it might take for the person to get their own copy.
Really the only people that could say I guess would be sales(at)avast(dot)com, but I don’t believe their answer would differ much from my guestimate.
If you are concerned about protection on his/your system, you could install a Pro Trial version on it, this would give 60 days unrestricted use. However you would have to do a clean reinstall as it may seem strange uninstalling and then installing the trial version (anti-piracy again).
Download a copy of the Pro trial version and save it to the HDD.
Download the avast! Uninstall Utility, find it here and save it to your HDD.
Now uninstall (using add remove programs, if you can’t do that start from the next step), reboot.
run the avast! Uninstall Utility, reboot. If step 1 failed it may be necessary to run this from safe mode, once complete reboot into normal mode.
install the latest version, reboot.
Sorry if this isn’t a positive answer but I’m just an avast user not in possession of the full facts.
Appreciate the quick reply…I was kinda hoping I would be able to take the easy road and just change the registration key number but deep down I guess I knew I may have to go the whole hog…
The other person will be buying his copy tomorrow when I deliver the machine - I have already steered him away from Symantec and while I am there I can install & configure it for him so it would be the best bet.
