Read recommends that all users subscribe to one of our paid plans to get the most out of the service. That said, only one person in the meeting needs to have a Read license in order to generate and share a meeting report, which includes a transcript, summary, recording, and meeting metrics (varies based on their plan and settings). While other participants in the meeting don't need to have a license, unless the Read user has link access set to public when sharing a report, participants will need to at least create a free account if they want to view it.
Free users cannot be part of a Workspace, so you will not be able to manage any users without a license in your Workspace Settings. Additionally, a paid license is also required if the user wants to get more than the 5 meeting reports per month that are included in the free plan.
If you are considering only purchasing one license and sharing the account between multiple people, please note that sharing accounts is a violation of Read's Terms of Service. Additionally, Read is designed assuming that one account belongs to a single person, so many features will not work or make sense if multiple people are sharing an account.