The only obligation was whatever was perceived by the licensee. The email was carefully worded so that it was clear that the license was free and clear, and, o

The only obligation was whatever was perceived by the licensee. The email was carefully worded so that it was clear that the license was free and clear, and, oh, by the way, it would be nice if you... For all we know they've done this a hundred times and received only "kthxbye" in return (but that's a valid response!).