Software for online lessons I'm interested in teaching online chess lessons to my students. 
But I haven't found any software plaftorm for this purpose. Are there any one? I don't mind if it's commercial or open-source.
There are several ways to teach online chess for free. 

1. Skype + Chessbase. An old version of Chessbase Reader can be downloaded for free (just google "free download Chessbase"). This program will have everything you need to play, analyze, and save games, along with many other options. With this program, you can use the "share screens" option on skype, where you have the chessbase program open, and your student can see the board on his screen. You can then proceed with the lesson via voice call. This is all 100% free.

2. Skype + Online Analysis Board. Some websites, particularly chess.com and ICC, have ways for two users to share a board, meaning that both can use the board. For example, on ICC (requires membership), you two can share a board, and make a call, and have the lesson. 

These are just two ways, and the first should suffice completely.