If advertising had a little more respect for the public, the public would have a lot more respect for advertising.
In the early days of computers, people often wrote and released programs as shareware. Unlike commercial software that you have to buy before trying, shareware lets you take a test drive first. Some shareware programs were fully functional, while others had features crippled or omitted or incorporated a time delay that made the program stop working after a fixed length of time, such as 30 days. This was done intentionally to entice people to pay for the full version of the program.
If people didn’t pay for the upgrade, the shareware programmer didn’t make any money, ...