It's difficult to find a cracked version. Installing a cracked version usually comes with a few viruses. Better to download the original and find a key or a cracked file script to run through the already installed original version.
I am a researcher (Silver-Medalist) in faculty of engineering (Electronics). In year 2017, after many struggles, I got a good one version, Matlab 2016a torrent and I use it up-today. But that torrent does not work efficiently, its expired!