In old Dynamics NAV, they had to buy an Application Developer license for 6000 euros to do that, and yet it was not allowed to modify a Codeunit 80 to for example fill out a field in the invoice. Only the 30 000 euro Solution Developer allowed that.
How does that work in Business Central now? Are they still allowed, if yes, do they have to buy expensive licenses like this?
Of course I mean development only for their own purposes, not publishing it.