I'm assuming you mean my comment and I worded it specifically the way I did - "if someone is seriously considering buying paid time" - because $3 can be too much for people but this isn't a question of how much is a month worth or how much people can afford for this type of service. It's a question of someone considering a paid account (ranging from $3/month to $50/year). The motivation, according to your suggestion, is "By having this, users can preview what it's like to have paid accounts and therefore, if they like it, they would be more inclined to buy it." But if $3 is already too much, then how would they be "more inclined to buy it"?