After the first time you log in with an email confirmation code, the Liteboxer app should remember your login and allow you to select the same profile afterwards. The code will be valid for 15 minutes. If you miss the time limit and your code expires, attempt to login again with your email to prompt a new code being sent to you, starting the time limit over.
By default, you should only be asked for a code once per device, then you'll simply need to touch your profile icon the next time you login: