The short answer
Before buying business software, ask whether it does exactly what you need, whether growth is a setting or a project, whether the vendor is reachable, whether reports still need building by hand, and whether the data stays yours. A "no" to any one usually means the software will cost more time than it saves.
1. Will it do exactly what you want — or only what the product allows?
Demos show the product at its best. Bring one real, awkward case from your business — a return, a split delivery, a special approval — and ask to see it done, start to finish.
2. Is adding a plant, a location or a product a setting, or a month of work?
Growth should be configuration, not a new project. Ask exactly what happens, and what it costs, when you open the next branch.
3. Is the company reachable when you need them?
When something stops on a busy day, a ticket queue is not support. Ask who you will speak to, and agree response times in writing before you sign.
4. Will someone still be building the management report by hand every month?
If the numbers management needs still come from an export and a spreadsheet, the software has not solved the problem that usually matters most.
5. Is the data yours — during the project and after it ends?
You should be able to take all of your data out, in a usable format, at any time. Ask how, and get it in writing.
If the answer to any of these is no
One "no" is usually where the hours go. Two or more means the software will cost more time than it saves. That is fixable — but it is far cheaper to find out before you buy than after.