On this, the writing app Ulysses for the Mac had my favorite trial. I think it was an 8-hour trial? But it was 8 hours of use. I remember coming back to it late in the day after downloading it and thinking, "crap! My trial." The timer hadn't ticked down at all, even though the app was open in the background. The timer only went down while I was typing.

I like a lot of the features of the app, but it would be a lie to say this trial thing didn't push me over the edge into a "buy."