Every demo is rehearsed. The vendor drives, the data is clean, and the workflow shown is the one the product handles best. You learn what the software is good at, which you would have found out anyway.
What you actually need to know is where it is weak, and you find that out before the demo, in writing, with questions specific enough that a vague answer is visibly a vague answer.
Here are twelve. We sell manufacturing software, so treat this as interested advice — but note that several of these are questions we answer badly, and we have said so.
On the product
1. Do you have a formula or recipe object, or only a bill of materials? Discrete BOMs assume you assemble parts. Process plants blend, and lose material doing it. If the answer is "you can model a formula as a BOM", ask how by-products and yield variance are handled.
2. What happens to a by-product? Many systems have no first-class answer and suggest recording it as negative consumption. That works in the ledger and not on the floor.
3. Is quality control included, or an add-on? Then: does it produce a certificate of analysis tied to a lot, out of the box?
4. Is scheduling finite or infinite capacity? Infinite capacity means the system will cheerfully plan more than the plant can make. Ask to see what happens when you overload a line.
5. What is expiry-first picking, in your product, called and configured as? If FEFO needs a warehouse module, a location setting and a strict-posting flag, that is three things that can be switched off by accident.
6. Which of what you have just shown me is standard, and which is a partner app? Write down the answer. This is the single question that most changes a three-year cost.
On the money
7. What is the total for my plant, over three years, including implementation? Not per user per month. The total.
8. Who does the implementation, and at what day rate? If the answer is a partner, the licence price you were quoted is a fraction of the spend.
9. What happens at upgrade time to anything customised for me? In some ecosystems, re-testing customisations every year is a permanent line item nobody mentions in month one.
On the awkward parts
10. What do you not do? A vendor who cannot answer this quickly either does not know their product or is not going to tell you. Our answer: Aourix has no general ledger. We hand journals to your accounting system and we never write into it. If you are replacing your accounting system too, we are the wrong tool and you should be looking at the big suites.
11. How many plants like mine are live on this today? Ask for the number, the industry and the size. Then ask to speak to one. A young product should say so — we are early, and pretending otherwise would not survive your first reference call.
12. Who supports me, in what timezone, in what language? For a plant in Indonesia being supported from California, the answer to "when does something break" is "overnight".
What to do with the answers
Send the twelve to every vendor on your list before any demo, and ask for written replies. Three things happen. The vague ones sort themselves out immediately. The demos get better, because the vendor knows what you care about. And you end up with a comparison document that is about your plant rather than about their feature list.
If it helps, our own answers to these are laid out against six other systems on the comparison pages — including the places where the other system is the better choice.