I purchased one of their products before. I was pretty satisfied. Then they started emailing me offering more costly products and I refused until I got involved in a larger project which would allow me to use and afford them so I replied one of them and they offered me a discount price and the only pending was the money transfer which didn't happened because the project was cancelled. All that time I didn't received even a serial number nor product so I thought the offer would expire on its own because there was no payment made like every other online store but it didn't. They kept mailing me and I replied I won't pay and I refused the offer but they told me I couldn't refuse now (later I discovered I actually could cancel it on the website but nobody told me that and now its too late according to them)
I think its unfair for them to request payment for something I'm not interested anymore and I wasn't able to use anyways.