Doesn't seem to be so there - maybe something will happen in the future to suggest they want cash (though I don't think that would make a good impression on users) but at the moment there isn't a hint that any payment is expected now or in the future.
I have been looking at the reviews. Only one of them mentions money (PCMAG which says it is free for a year) but none of the other reviews mention this at all, and there is nothing on the website to suggest it?