Paid adds-on on student version does not work

Dears,

I experience a very strange situation which is taking too much time and still I can not fix it.

I paid for the student version and the Aerospace Toolbox. In my account, I can see that they are not expired. I wanted to try the SimBiology app. So I followed Matlab instructions which was requiring to install a trial version in which this simbiology was available. So, now if I look my account, I have two licenses. One student and one trial. I know that I can switch from one to another by choosing Activate software from Home - Help -Licensing. By doing that, Matlab displays "student License -- for use by students to meet course requirements and perform academic research at degree granting institutions only." So that means I am back to my student version and I should be able to use the Aerospace Toolbox that I was using before the installation of trial version. However, this is not the case and I have the following error : " 'flowisentropic' requires Aerospace Toolbox.". So I went more than 10 time in the add-on explorer to install again this tool. By looking for this tool and choosing the option "install', matlab asks to be closed in order to install this tool. So, one would think that everything has been installed correctly and that is why Matlab closes itself. However, after opening again the matlab software, there is no trace of installation of this tool and I have the very same error. In conclusion, nothing has been installed ...

Could someone tell me why that is happening ? What is the solution ?

Regards,

Mary