GrokBot + Toolbox Conversation (runs)

I am informed there are 50 runs a month allowed in the connection. Does one “run” equal a single dialog or a single send? For example, let’s say I am using Developmental Editor and it evaluates my story. I want to ask follow up questions (move through several parts of my novel with DE) through GrokBot. Does each single step (Question-send) in this process cost one run? In the class you ( @Thomas Umstattd Jr. ) said it would be a better use of tokens to go through Toolbox. How does that work exactly?