IKinema RunTime available to small and indie studios for £99

This is a good point. On the website you say the following:

*Do I need to upgrade and when?

We are adding new features and from time to time we might ask you to upgrade for a small fee of £30.*

Can you clarify on the frequency of these payments? Will we have to pay £30 on every upgrade/new feature? It’s not clear as you say ‘from time to time’. What does that mean?
I don’t want to be nickel and dimed for every single upgrade through out the course of a year.