Well, unito.io will be releasing a connector to automate this type of task sooner than later but for the time being you could check out this guide to get r’ done.
@Luca Loeffler -
The simplest way to do this would be to share the board from the free plan with someone from the paid account team, and then they could either duplicate the board or copy the content from the board to one within the paid account. The free account team would show up in the left column of their Miro dashboard and they could switch between that and the paid account team.
Kiron
Luca’s solution does not work. I tested this. Content can be copied from the Free board, and pasted into a board in the paid-up version. However, once there, the content cannot be changed in any way, shape or form. You can’t move objects around, you can’t edit them. You can’t even delete them.