If you want to use the microphone feature when speaking with MemBot, you will need to enable microphone permissions for Memrise. You can do so by following the instructions for your browser below:
How to enable microphone permissions on Google Chrome
How to enable microphone permissions on Mozilla Firefox
How to enable microphone permissions on Microsoft Edge
How to enable microphone permissions on Safari
If you're looking to enable microphone permissions for the Memrise app, see these instructions.