Here are some common questions and answers that I've collected:

Q: Where do I put my license file?
A: For Windows: Put it into this folder: c:\Program Files\Subsonic Labs\Wolfram
(if you've installed Windows to another drive, replace "c:" with that drive letter)
For OSX: Put it into this folder: /Users/martin/Documents/Subsonic Labs/Wolfram
(replace "martin" with your own user name)
For both Windows and OSX: The "Subsonic Labs" and "Wolfram" folders should already have been created by the installation program.