This is a question I was just about to ask because, as you say, their website is no help whatsoever.
I find Hitman Pro quite useful but I have D7 (original flavour) and use it from there. This works initially (even used it today River Valley, so may be something wrong with your D7?) but it only gives a thirty-day trial licence. If you get the same machine back in 6 months or a year and run Hitman Pro on it again, it says the trial licence has expired and you must now buy it for it to do its job.
So which pricing option works in a 'one-man band, working residential only and not making much money so can't afford much' scenario