Power-Ups turn Trello boards into living applications through additional features and integrations. Boards belonging to free users can turn on one Power-Up at a time, boards belonging to Trello Gold members may have three Power-Ups turned on at a time, and Business Class boards can have unlimited Power-Ups.
All teams will also have access to the Trello App for Slack.
Enable Power-Ups by selecting “Power-Ups” from the board menu and then by clicking on 'Enable' / 'Disable' to activate or deactivate the Power-Ups you would like to use. You have to be a member of that board's team to enable Power-Ups.