Hello Andrea,
There is a very big difference between how you can work with MATLAB on a computer, and how you can work with it with a tablet or phone. On a computer (desktop, laptop, notebook), you can install MATLAB locally. It will contain all the libraries and files necessary to run, and can be used without internet (once installed and activated). All features for the toolboxes you own will be usable from your system, including some of the Windows-specific features (e.g. COM integration).
On a mobile device (tablet, phone, etc.), you can install the MATLAB Mobile app. This requires connection to either a cloud-based or computer-run session of MATLAB, meaning you need internet access to use it. All computation is done in the connected MATLAB session, not on your mobile device. This means that it will take less memory and processing power, but it will also be significantly slower (at least for some operations that require a lot of data to go back and forth). There are also several built-in apps and features that are not yet supported by MATLAB Mobile (see the "Limitations" section on the page I linked).
I hope this helps you make your decision.
-Cam
