Tengo entendido que el número de 'trial lessons' no es solamente limitado, pero es permitido solo 1 con por profesor. Es decir no podrías tomar 2 lecciones de estás con el mismo profesor. Saludos

@Guyomar: That's really interesting; I was unaware of that limit, but you're right: http://support.italki.com/hc/en-us/articles/206352248-What-are-Trial-Lessons- "The purpose of offering trial lessons is to give a way for students to get to know the system, not a way to get to know the teachers." I assumed that their purpose was the latter. At a guess the limit of three is because Italki doesn't take commission on them: http://support.italki.com/hc/en-us/articles/206351548-Offering-Trial-Lessons

3 total only - it's supposed to be a way to familiarize yourself with the site although many teachers use it to give a demonstration of their teaching style.