The Enter key in the Message App doesn't exist, When you use the motorola moto g for texting, by default you will not find the enter key. The button is missing from the keyboard and replaced with a smile button. Where you can add a character takes a lot of emoticons for SMS.
Here's a screenshot of default keyboard while using application message default android kitkat. Whether linked yours also so?
The enter key at the bottom right corner has been changed with the smiley image. So you can not do enter on existing sms you type. But often we need enter to give distance while making it easier to read.
How? Very easy is not it? Hopefully a simple android tips tricks can help friends who have difficulty finding the enter key while using android sms via kitkat. This problem does not occur if you use whatsapp.