Why is the "free plan" not free?

[Gerhard_M_]

I use Trello in the free version with 4 users and one app (Chronos). After we have worked with it for some time, the app Chronos was been shut down, with the given reason that Altlassing has to earn money especially due to Corona. We are said to pay a usage fee to be able to use Chronos again. Alternatively, we should reset Chronos so that we can use it again for a while. 

So a problem-free use is not possible for free.

Why is this not mentioned anywhere?

[Michael Pryor]

We have an app marketplace called Power-Ups. Sounds like you installed one of them but that isn’t Atlassian (or Trello) trying to charge you. 

[Gerhard_M_]

Before I installed Chronos, I was told that I could add now one app for free. After that I was informed that the contingent was exhausted: "This board has reached the maximum number of power-ups.". The description of Chronos does not contain any reference to fees. Sorry that this is all quite confusing for me.

I understand, that a company should earn money for services. Not a problem. My company also charges such fees itself. However, I think transparency is important. Otherwise, I could be annoyed if I feel I have fallen into a trap.

[Steven F Behnke]

Chronos is a third-party paid plugin. It does not exist in default Trello as far as I am aware.