You can't redeem the points. You get points for interacting with the website, by asking and answering questions from other users, or by paying for the tutors, etc.. They are basically there so that other users can tell how serious you are, I guess. For example, if some guy messages you and wants to be a language partners you can check out how many points does he have. Is he an active member of the community, or did he just drop by to chat with girls. I think they're also a kind of meaningless reward for being on the site.

@Karl

I don’t think that you receive points for taking paid classes. As far as I you only receive points for community activities.

@Karl

Yes, but it is useful to some extent because users who do have some points seem to be more trustworthy than those who have none. Users who have a lot of points are helping others a lot because you receive more points for offering help (by correcting notebook entries, that's 30 points I guess) than for asking for help (10 points). Su.Ki for instance has close to 300,000 points, which means she is doing a lot for the community: <a href="https://www.italki.com/user/1478711" target="_blank">https://www.italki.com/user/1478711</a>;.