Most billing software demos look identical. The differences show up on day four, when your counter is busy and the printer is warm.
1. Can it be operated without a mouse?
Time a full bill of ten items using only the keyboard. If the cashier has to reach for the mouse even once per bill, multiply that by your daily bill count.
2. Which printers are actually supported?
Ask for a live print on your own thermal printer, not a PDF preview. 58mm and 80mm behave differently.
3. Who holds the database?
Get it in writing that you can take a full MySQL backup whenever you want, and that the software will keep running if you stop paying.
Building something similar?
We will tell you honestly whether a ready product fits or you need a custom build.