I'm not the author, but generally: It could depend on whether those trial users are worth supporting. You could potentially get a free-rider problem. You could get a lot of support emails from people who never convert anyway.

It's only 10€, so it's pretty well in the impulse-buy category.

To the author: I'd suggest localising the currency, if possible. At least for English speaking locales (US, UK, CA, AU, NZ). The EUR pricing made it look to me like you might not be able to buy it if you're not in Europe. (Edit: I'm in Canada and it shows EUR, not CAD.)