Lots of teething issues with it at moment, cannot enter thailand as place of residence so cannot put a thai telephone number in hopefully have all these issues sorted before it starts.
If it is like Singapore & Malaysia you dont show anything the IO will know if you are registered or not. This should hopefully end up like Singapore and Malaysia where they are automated entries as well now. You got to look at the bigger picture
Lots of people are having difficulty getting back to back visa exempt tourist entry. You will not and can get nearly 9 months in Thailand if you work it out correctly