I have been using SoundTap for many years; my current version is 2.11.
If I recall correctly, when I first tested the program trial version, it did have a background 'voice' saying something like "you must purchase the software..."
Perhaps the popping sound that is referred to above is the same sort of thing - you can try the software for free to see how it works, but to do a proper recording you need to purchase.
This may just be conjecture on my part - I am mainly posting in this thread for future readers who might shy away from the product because of the above posts.
While it may be true that a satisfying answer to a question in these forums is not guaranteed, this program has worked like a charm for me on both xp and windows 7.
One thing that I recommend when using SoundTap: close all programs and browsers before starting up SoundTap. Then proceed.
My main use is to record streams from the internet. Once I set the destination for the recording and 'start recording' I do not use the computer for anything else until my recordings are finished.
This way no background 'noises' will interfere or be recorded.