Hello Hector,
Implementing a usermat routine, which is a User Programmable Feature (UPF), typically requires an enterprise license. I don't believe that the student version features this capability. One way to check this is to see if the "custom" folder exists in this path:
C:\Program Files\ANSYS Inc\v242\ansys\custom
This folder contains the files necessary for implementing UPFs.
You are navigating away from the AIS Discovery experience