I like this site and I want it to stay around. So, I want to offer my humble advice.
First, the audio lessons are the heart of your service. They should be what you are charging for. The kanji files and quizzes and stuff aren't so important. Plus, they are things people can get from many books. The audio lessons are unique. They are interesting, funny, well structured, and I can easily put them on my mp3 player and listen to them whenever I have a free moment where ever I am. They are what makes the site worth coming to.
So, you should not have them for free! Have one lesson that does not change that people can listen when they visit the site.
Second, and this one I am not sure of but I want to throw it out there, have only one subscription level. That one level includes the audio, the most important thing, and then all the other stuff that you want to throw in. But really, even if it was only the audio and maybe the transcript, that would be enough for me to subscribe!
Third, don't let people on the 7 day trial be able to download every lesson from your archive! A smart person will download everything you have in the 7 days. Then, what incentive do that have to become a subscriber? They have enough material for a number of months. New lessons only come out once a week or so for each difficulty range.
When they get through the material they downloaded during the trial, they could get a one month subscription and do the same thing. Not really good for business.
Once again I really like the site and I hope it sticks around for a long time! I think you really know what people are looking for when they are learning Japanese!
