During the trial period, you can invite just as many users as you want. At some point, we may implement a feature that allows the change of your email address. If you want to change the email address after the trial period has ended, we suggest you to ask your account admin to remove your user and then invite you with the new email address. This way you don't have to pay for additional user (as we add credit for the deleted user to your account).
No data will be removed if you need to remove a user. So, you don't have to be afraid that you couldn't access the data in case you need to add a new user and remove the old user account.