careware
n. Computer software in which the only "price" is to do a good deed or donate something to charity.
Etymology
Examples
2002
Do you need to design a Web site? Microsoft's FrontPage is a very capable program, but the 2002 version lists for $ 169.

Instead, try Arachnophilia (www.arachnoid.com/arachnophilia). This is a nicely featured program and is "careware." The author wants no money at all for his program. Instead, he asks that you "stop whining for an hour, a day, a week, your choice, and you will have earned your copy of Arachnophilia." That's not a bad deal at all.
—Kim Komando, “Programs you can download for free,” Gannett News Service, April 01, 2002
1993
Winmap shows the memory use of programs in use. It is a bit esoteric, but its author, Olaf Wess, from Germering in Germany, charmingly offers it as "careware" — there is no fee, but if you use it, he asks you to donate something to someone in need.
—Nigel Wilmott, “Be an addict on the cheap,” The Independent (London), November 19, 1993
1992 (earliest)
The software is free, but if you'd care to, stuff a dollar bill in the mailer for the Brevard County Food Bank. They help the homeless and hungry. We call it DDJ's "careware" program.
—Al Stevens, “Software Development '92 and D-Flat dialog boxes,” Dr. Dobb's Journal of Software Tools, June 01, 1992