I have had a trial running on my site for about 6 months, but I removed it again. What happened was that people log in, watch all the video, then cancel the trial. When removing the trial, my member count dropped, but my revenue increased.

I just saw on another platform an interesting option where, if activated, a trial user only gets access to 3 videos (I assume the trial user can pick his / her own 3 videos). That would be cool and would give a trial more strategic value.