How much does it cost to update Cornerstone?

I bought a Cornerstone plugin many years ago. Now my it-guy tells me that I should update it, I don’t know why, and I can’t find the price for doing it or where to download the update. Can anyone help me please?

I’m not looking for a service agreement. And my level of knowledge is that I don’t know the difference between Envato, Themco and Cornerstone.