Redline definition is - a recommended safety limit : the fastest, farthest, or highest point or degree considered safe; also : the red line which marks this point on a gauge. The Red line, or "to cross the red line", is a phrase used worldwide to mean a figurative point of no return or line in the sand, or "a limit past which safety can no longer be guaranteed."
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.