business class subscription vs add in subscription

[Jeff Quinn]

Business Class offers unlimited power ups for a fee.

One of the power ups I added also wants a fee.

This is confusing...how much does it cost so I can use the add in?

( add in being used is blue cat reports )

[Michael Pryor]

We have an ecosystem built on top of Trello so other developers can build and market their products to our users. 

Blue Cat Reports is a power up written by someone who has added a paid service to Trello (like apps on the phone). 

There are power ups that are free (all the ones that were written by Trello are free) but if you are not a paid Trello user you can only use one power up per board.