can i have multiple audio on several tabs?

Within the Editor screen you can have only one tab open at a time, i.e only one file "active" in the Editor screen.  In order to switch between different files there is no alternative to opening and closing them using the method you've mentioned, or by simply double-clicking on the file name of the one you wish to work on.  The current state of the file that was previously opened will be written to your designated Audio Temp drive but not "saved" until you choose the option to Save, Save all or Save as.

I guess an alternative is to open all 8 files on 8 tracks of the multitrack screen and simply select the one you wish to work with by soloing its track.  I've never tried this but I think it should be possible.  The only thing you would have to remember is, once you have finished work on your 8 tracks you would need to export them individually in order to "save" the new version(s).