Two weeks ago I asked operators which system a seller called transferable that turned out not to be. Three answers came back.
Jason Nappier named rare-cycle work: certificate renewals, annual exports, systems someone opens twice a year. Daily work gets tested by use. Rare-cycle work does not, and you find out after close. His test is a named calendar for everything the business uses less than once a month, with a transition term long enough to span the longest material cycle.
Another operator kept his test to one line: have someone other than the seller run the process start to finish. If nobody can, you bought the software and left the ability to operate it behind.
The third answer came from an operator who inherited a manual timekeeping workflow. It transferred without a hitch. He then lost hours to it, and his staff pushed back when he tried to change it. "Can it run" is the easy half of the question. Ask who touches it, how long it takes them, and where the work lives outside one person's memory.
I turned the three into five rows: critical workflow, company control, operator and backup, exception path, and one live test. If you are under LOI and want the five rows, ask and I will post them in the comments.