Technical writing and documentation

Instructions people can follow: product manuals, help centres, API references and the internal procedures a growing team stops being able to hold in its head. Usually bought when support questions repeat.

Yes, in some form. A demo account or a walkthrough makes the difference between documentation that works and text that describes a guess.

Ask for it as a retainer if the product changes often. Documentation written once and left alone is worse than none, because people trust it.