Two of my friends experienced this problem where they downloaded the software and opened it up, once they tried, they had a problem with Windows Voice Packs, which required a restart, upon restart, they weren't able to open up VoiceAttack again because they would end up on a Trial Expired screen, even thought they barely had it on their PC for one hour.
This will obviously get fixed by purchasing the key, but it's hard to convince them when they didn't even try the app.