Thank you, @Martin !! Not sure if it was posted previously, but to get the license working I simply copy and pasted the key.txt file into the folder containing the .exe and .ini files. HWiNFO automatically recognized that it was in the same folder.
I use HWinFO (free version) on multiple computers. Wanted to confirm the following:
Buy one license and upgrade is paid for on each of my computers (up to 5).