I am not sure we can to be honest. The site will run itself and will not need much in the way of support. We imagine the user may be willing to pay a fee for a number of benefits that they will get from the site. However, if I put myself into the user's shoes, then I would definitely pay a one off fee for the benefits that the site gives but I am not sure I would be willing to pay a monthly fee.

I am the type of user who is willing to pay $10 a year and gamble on something as I have only lost $10 - I can then forget about it if it does not work out. However a monthly fee I found off putting - the thought of money coming out of my account each month until I cancel (which I would probably be too lazy to do) puts me off. That's why I think app's work so well for Apple. I pay a one off fee and I forget about it.