Looks like a very good software. Is there advertisement in the software? How do you get access to free music?

No.  There is no advertisement in the software.  At least, not in the paid version.  I have no idea whether a trial version exists or if advertisement is shown in it. 

In regards to how you access the free music, AudialsOne has several options to it.  The program has a database of streaming radio stations (you can add your own).  You select the stations you would like it to monitor.  It will then "listen" to the stations and capture the audio from them.  It uses whatever bit rate the station broadcasts in.  It then "cuts" the audio into tracks based on queues sent by the radio station.  Those are then converted in the format specified by you. 

You also have the ability to filter it to search for specific artists or tracks.  The same principal applies for the radio stations except it looks for the track(s) you ask it to look for.

Then, you have certain sites where you can capture live feeds from, such as Last.fm or in the new version Grooveshark.  It will recognize when you select a track to listen to from one of these sites and "capture" it the same way it does with the radio streams.

AudialsOne also provides you the ability to rip the audio out of video tracks from sites such as YouTube.