Me personally I don't care, I'm not making anything I'm going to sell, but you should be aware if you are
> 7.2.2 For any Public Document owned by a Free Plan User created on or after August 7, 2018, or any Public Document created prior to that date without a LICENSE tab, Customer grants a worldwide, royalty-free and non-exclusive license to any End User or third party accessing the Public Document to use the intellectual property contained in Customer’s Public Document without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Document, and to permit persons to whom the Document is made available to do the same.
[0]: https://www.onshape.com/en/legal/terms-of-use
Perhaps more importantly, the Free License doesn't allow for any commercial use. If you are designing something for commercial use, then you can, should, and are obligated to, upgrade to a paid license.
The sales rep called me and seemed miffed when I said we're not an engineering firm, and we do not need CAD for our line of business. Sorry buddy, but my use case is for a commercial purpose (not for sale but it is designed for and would be used by a business...) so I can't really sign up for the free hobbyist license that explicitly prohibits commercial use and fails to clarify exactly what that means.