Someone in past threads mentioned that many digital sales website in fact no longer use "buy" anymore, and instead deniably implicate purchases by such expressions as "Add to Cart", "Proceed to Checkout", and "Pay".

Yes, all this talk about the language used still leads us to the same frustrating outcome: customer pays for something, and at some unspecified point in the future that same thing is taken away from them. I don't care if 6 years earlier I clicked a button that said Pay vs Buy, I care that my purchase is being removed due to some backroom licensing issue.

Wonder if you could have those buttons and not give the user anything at the end, since you never said they were buying anything, only giving you money.