I paid for it because I like the color-coded days, and the fact that you don't hve to count dpo for yourself (it does that for you). I like the other stuff too - charts overlay, and early pregnancy signs. I have never used the forums - I use mdc enough, and don't need to spend any more time on some other forum

It is not really necessary, but it was not too expensive, and I do like it. I pay 6 months at a time (I have renewed once, and I will hopefully have a bfp before I have to renew again.