Hi Zhou Ke,
As you can see in the image below, there is a space character in the full path to the mex file "sim_spt20_mex.mexw64", which in fact contains the SPT 2.0 simulator, so the license tool will not work.

If you say that the toolbox works on MATLAB 2017b, but not on MATLAB 2018a, that means that you install it once on MATLAB 2017b and once on MATLAB 2018a. There is no need to install it on MATLAB 2018a if you install it on MATLAB 2017b. MATLAB 2018a can see all the toolboxes installed on MATLAB 2017b. In order to be sure of this, can you send me an image with the list of add-ons from both MATLABs? You can find the list of add-ons from "Home->Add-Ons->Manage Add-Ons".

The image should look like this:

Also, I will need the result of the command "which add_mex" from both MATLABs.
Thank you,
Iulian Bulancea