How to track unique visitors in a private online store?

We have a list of 500 people that we would like to invite to an early pre-order of our product. Is there a way to limit access to our store to only those invited? We would like to be able to track who accessed the store, and who did not.

We could simply set a standard password for the whole store, however, we wouldn’t be able to track unique visitors if we went that route.

We are using the Dawn theme.

Interested in this as well. Using the Craft theme.