Do you mean
this one? http://download.cnet.com/Online-Yearly-Calendar-Any-Year/3000-2077_4-10915220.html?tag=rb_content;contentBody
If so, I tried it myself using LibreOffice which is just an open source word processing suite including a spreadsheet that can open and edit Office files.
Frankly I am stumped!
It works, but all it allows you to do is input a new year and so display the correct calendar for that year. I could have created a calendar like that myself but I don't bother because I get so many free calendars posted through my post box I have never had to purchase any calendars.
And when I say it works, that's not the whole story. When I click the cell to change the year LibreOffice halts with a "Not responding" message for a number of seconds, and then continues. I can then enter a new year, then it halts again before displaying the correct calendar.
It's all pointless.
So as far as I am concerned it is free. I did go to the web site but I didn't bother registering or signing any invoice, but I don't see myself using this at any time in the future.
If you feel the same you may want to "be the first" to add a comment on your experience with it on that page I linked to.