Donationware

Unlike shareware there's no trial and no obligation; the program is fully usable and a donation changes nothing legally. In licensing terms it's usually freeware or open source with a payment button bolted on. What differs is the expectation, not the terms.

One branch is called careware or charityware, where the money goes to a good cause rather than the developer. The best-known example is Vim, whose author Bram Moolenaar spent decades asking happy users to donate to ICCF Holland and children in Uganda. These days the model has moved to platforms like Patreon and Ko-fi, but the underlying arithmetic hasn't changed: a sliver of users pay, and most projects support nobody.