You're not fooling anyone. You're assisting your user in navigating organizational complexity required to pay a preferred software vendor.
At my previous companies, the only thing I would need to purchase software was an invoice/receipt I could point to to show that I had purchased a software license. The contents of that license don't matter, and in fact, I even told a few projects "Please invoice me for a commercial license of your software. If you don't have a commercial license, I will accept your existing [e.g. MIT] license as a commercial license. If you do not have a price list already, I will accept a quote of $1,000 without any further negotiation required; just send me an invoice for it."
I think that software developers are really weirded out that the same bits can be free-as-in-beer and _also_ cost $1,000. [+] But _software buyers want to purchase outcomes, not bits_. The outcome I want to buy is "$PROJECT continues to exist in the world." I have sufficient internal authority to purchase this outcome, as does the other commentator on this thread -- we've announced that fact loudly, as does anyone else who either requests a quote or actually pays you. I have sufficient legal authority to purchase that outcome as an officer of the company I was employed at, which enjoys an incredible amount of discretion in how it chooses to spend its own money in the pursuit of its legitimate business objectives, and which has chosen to invest that discretion in me. Reasonable third parties might disagree with our expensing policies (or think they shouldn't have hired me), but reasonable third parties don't get a vote.
[ + ] I sold trial-based software, and a fair bit of it, for many years. The difference between a trial version and a registered version was... nothing at all, if you just compared the binary artifact. The sole thing that distinguished the two was that, if you proved to the software's satisfaction that you were a paying customer, it would act like it was registered (displaying that fact and removing the trial limitations). This was, literally, a single if statement.
Could I have sold software on that same model without the trial limitation at all? Clearly yes; registration would then only cause the software to display you were a registered user. Could I have sold software on that same model with the only display that you were a registered user being outside the software? Yes. How about if that were _only displayed on the purchase confirmation email itself_? Absolutely freaking fine.
None of this gets harder or legally murkier with OSS in the picture.