Later, I noticed on the ST website that there is a license agreement for the board. (To be clear, I did not agree to the license when I purchased the board from Digi-Key, not even in a click-through fashion.)
What disturbs me about the license is that it seems to apply not only to the software/firmware, but to the physical board itself. And it states that:
STMicroelectronics (“ST”) grants You the right to use the enclosed Evaluation Board offering limited features only to evaluate and test ST products solely for Your evaluation and testing purposes in a research and development setting.
It's not clear that my use would be "evaluation and testing," since I intend to actually do something useful/practical with it. (i. e. I am a maker and intend to incorporate it into a project I'm building.)
Furthermore, the license says that the board may not be resold. Although I'm not really intending to resell it, I would generally consider something I bought to be fair game to eBay when I'm done with it and don't need it anymore. How does this restriction fit with the Doctrine of First Sale?
I intend to use open source software on the board, to the extent possible. Though there are possibly some bits of the firmware (maybe the bootloader, for example) which are closed-source and cannot be replaced. Does the existence of this firmware on the board mean that ST Microelectronics can control what the board as a whole is used for?
As a hypothetical, could the manufacturer of a washing machine include a "license agreement" which prohibits selling the washing machine to someone else when you don't need it anymore? (And if the answer is "no", what makes it different than my situation?)