The tool only registers up to one minute of recording, but has unlimited uploads. To cancel before addressing the contact, drag the audio line to the left, towards the trash can icon. Anyone who regrets the content can still press the audio message and choose to cancel it, the message deleted for everyone in the conversation. However, this does not prevent the recipient from having already heard the content.
As with WhatsApp, it is possible to "lock" the recording to avoid holding the button at all times. To do this, simply press the option quickly and drag your finger upwards towards the red lock symbol.