In answer to your question, you need to understand that teachers set their own prices. When they start on iTalki, they usually set their prices low to attract students, but after a while, when they start getting a lot of requests for classes, they will (usually gradually) increase their prices. It's a question of supply and demand. If you are much in demand as a teacher, it seems logical to charge a little more. There is however always a wide range of prices for most languages. So if one teacher becomes too expensive you can always switch to another. In some cases, teachers will keep a special price for "old students" to reward them for their loyalty. If you look at the the class names you will sometimes see this. You could perhaps ask your teacher if he or she would be willing to give you a special price, especially if you have had quite a few lessons with them already...

Thanks everyone for your advice. I don’t mind paying a bit more, as I have a very good teacher and enjoy the lesson but Does this mean the lesson keeps going up in price? It all seems a little wrong to me. Thank you all though.x

or change your teacher to a cheaper one.

The cost depends on the experience, the qualifications of the teacher and above all the requests for lessons they receive. You have probably chosen a teacher in high demand. If you think the teacher is helping you o improve ask them a lower price, maybe you will find and agreement. If not you can find another one, don't stop studying italian!

If it’s for a specific teacher than you would need to ask them. But There are tons of teachers so you should be able to find someone who fits your budget.