I don't know the Hudl specifically, but this generally applies to Android devices:
If you haven't already, enable the 'Developer options' settings menu by going to the About page and clicking on the build number 7 times.
There's an option in there that allows you to enable an overlay showing running processes (a bit like like top, or task manager), as well as some things for tweaking the number of background processes that may be helpful.
Free memory isn't particularly meaningful in Android, as by design it tries to keep it as full as possible, to speed up task switching, and processes are only killed when it's needed for something else.
(There's also a useful 'show touches' option in there which really ought to be in the accessibility options, as I find it greatly improves the accuracy of the touch screen by providing visual feedback.)