There are a few restrictions when you use MusiCAD without registration (license), so you will have to get accustomed to a few itches:
MusiCAD files are stored uniquely encrypted for use on that specific computer. If your computer dies your files become just as unreadable as on any other computer;
You cannot share your MusiCAD-files since they are encrypted. If you'd like to share you music - in editable form - with others you have to register (and pay the license fee);
On each printout a small message will be shown;
MusiCAD will remind you that registration is preferred every once in a while;
To get rid of the aforementioned restrictions you'll have to register and pay for a license.