A:Answer You can have as many devices logged into the same account as needed, and if you'd like to have guests access the account, you can set up a family account so you don't have to share your personal login information with them.
Details here: https://nest.com/support/article/Learn-more-about-Family-Accounts-and-inviting-people-to-access-your-Nest-home
Both the Nest E, and Nest Learning Thermostat have the same functionality through the Nest app.