You don't indicate which flavor of i1 you've got. X-Rite uses "i1" as a brand
name and they make a number of significantly different devices under that
brand, including colorimiters which are only physically capable of profiling
displays. And I'm not aware of any i1-branded device which uses dongles to
enforce display-only access, though they and their predecessors have
definitely used that method for other products, especially older ones.
Wouldn't a gray background be better for measurements?
The ideal background is the one against which prints will be displayed. For
example, if you're mounting prints, you'd want to use the actual mat board
the print will be mounted to for the backing. For a book, you'd want to use a
stack of the paper thick enough to be opaque. For something reasonably
generic, you'd use something as close to white as practical, with a number of
OBA-free fine art papers being good choices.