With the free version you can only create 3 public boards per month, there's no limit on the number of people who can use and access the boards and there’s no limit on the number of people you can invite to a board. To find out more detailed information about the free version, click here.
With the paid version you’ll have all the benefits listed above plus depending on the plan you choose, you can have more public boards and create more teams. All the paid plans offer unlimited team members and unlimited team boards.
Also, once you signed up for a paid plan, you'll be able to:
· See the history of your retrospectives
· Add/remove people and make sure that only they will access your boards
· Enable Slack and Confluence integration
· Export your board into multiple formats
· Delete all cards and votes of a board
· See the analytics board with basic information about your retrospective
· Add surveys and polls to a board
To find out more detailed information about the paid version, click here.