Here's another failure of marketing on my part.

We included full library source with the compiler, for free. No reviewer ever noticed that. One day, Borland decided to make source code for their library, sans the floating point stuff, available for an extra charge. This generated headlines in the next compiler roundup article. No mention that complete library source code, including floating point, came with my compiler.

So we decided to split off the library source code into a separate package, and charged for it. This solved the marketing problem, and doubled the money we were making.

This was how I learned about the common practice of upselling. I am a slow learner.

Of course, these days we give away everything for free!