SESSION variables query

We've recently moved to a new host and it looks like for various reasons we can't use $_SESSION variables.

In h5p.classes.php line 3072 there is a hashToken method that uses $_SESSION.
I'm not entirely sure what it's purpose is, other than to create a unique key, but are you able to tell me what would happen if this method no longer worked reliably?
Kind regards,

Alex Furr