1. Software that has some important functionality deliberately removed, so as to entice potential users to pay for a working version.
2. (Cambridge) Guiltware
that exhorts you to donate to some charity.
3. Hardware deliberately crippled, which can be upgraded to a more expensive model by a trivial change (e.g. removing a jumper). A correspondant gave the following example:
In 1982-5, a friend had a Sharp
scientific calculator which was on the list of those permitted in exams. No programmable calculators were allowed.
A very similar, more expensive, programmable model had two extra keys for programming where the cheaper version just had blank metal.
My friend took his calculator apart (as you would) and lo and behold, the rubber switches of the program keys were there on the circuit board. So all he had to do was cut a hole in the face. For exams he would pre-load the calculator with any useful routines, put a sticker with his name on it over the hole, and press the buttons through the sticker with a pen.