[cannam]

I don't know whether this has changed, but they used to forbid you from developing with the open source edition and then releasing under a commercial licence. (They did this with a term in the commercial licence that specified that it couldn't be used with code previously developed with the open source edition.)

This was quite a confusing policy in some ways. I think in practice they expected to resolve such situations by backdating payments for the commercial licence to cover the development period.

(Edit: from https://www.qt.io/faq/#_Toc_3_13 it looks like the policy is unchanged but the wording around it has been softened a bit to encourage negotiation)

[bluGill]

That is the license terms, but so long as you haven't distributed it before you go to sales and explain the situation they are willing to come to an agreement. Probably this means you pay for all the license term you should have. Something to that effect is even on their pages if you dig around.

The important part is once you realize you have the wrong license you contact sales admit your mistake and make a good faith effort to correct things.

[jononor]

3.13 (and 3.12) sounds primarily for avoiding that a company has 30 developers with only the 1 developer (or CI bot) that does the release having a Qt commercial license.

Or that you develop for 12 months and get a commercial license the last month,, when its going to be released.