In case you haven't figured out, this program can run portably. All the instructions are in a file called portable.txt under your install dir. Here's the instruction part of the text:
Perform following steps to run AnVir Software program as portable application:
1. Install the software.
2. Copy AnVir.exe and VirusTotalUpload.exe (optional) to the destination folder.
3. Create anvir.ini in the destination folder. If file anvir.ini is found in the folder of executable, all setting will be stored to this file instead of registry.
4. Copy all files from "c:\Documents and Settings\{user name}\Local Settings\Application Data\AnVir" to the destination folder. If file startup.dat is found in the folder of executable, all extended setting will be stored to this folder instead of "Local Settings" folder.
I recommend that you copy the entire program folder, delete portable.txt from your USB drive, and follow the rest of the instructions. Reset all your settings, and then re-enter the key to make sure that the program stays registered (I haven't tested it yet; if it doesn't, keep a copy of the readme.txt from your giveaway package and use the key there to reregister the program.