Examination fees

I am an accounting student and have little concern with regards to the system we make our payments and possibility of any interest involved in the payments. Our payments include the examination fee payed few days before the examination session and an annual subscription fee to remain an active student.

Firstly, the examination payments can be made in three periods. The earliest the payment made, the lowest would be the payment. However, sometimes due to late examination decisions the early payment period passes by and we have to make standard payment that is higher than early payment. Is the difference between the early and standard fee considered as interest? I have heard that all penalties arising due to late payment are haram and therefore the higher amount payed as a result of not being able to pay in the early period for some reason a kind of penalty. It is also possible that the extra amount is to encourage most students to make payment as early as possible.

Second, I have heard that the annual subscription payed every year to remain an active student involves interest. Is that true? This would be a lifetime payment even after I qualify to remain an active member. Does it involve any kind of interest or penalty?