We ideally want something clean and that can become iconic. We would like people to be able to see the logo and know the brand immediately (much like - Apple, Chrome)
Please dont incorporate any QR Code symbols into the logo, it must be representative of a mobile productivity / utility app.
If you use fonts that require a license, confirm with the client they're ok with it. For licensing reasons, it is better to provide your client with information on how to acquire the font rather than providing the actual files.