Why does filetram provide its services for free?

There are also a lot of limitations and some features would be able after buying premium but anyway this is profitable!
1 premium account on filetram cost 10$ per month but if you will buy premium accounts at 64 file sharing services that are included at filetram's base you would pay 640 $ - clear advantage. But i am not "advanced" in this theme:) You should read their blog if you are interested in.
Source: http://blog.filetram.com