Two things I can think of.
1. Alter your Java heap size
To adjust the Java heap size:
On the Home tab, in the Environment section, click Preferences. Select MATLAB > General > Java Heap Memory. Select a Java heap size value using the slider or spin box.
2.Depends on the code, are you generating a lot of figures? I have memory issues when I do that, it helps to save them and then close them. You still have them then to add to a report but don't need them in memory.