I have a custom vending machine attached to Outpost through Monument addons. I only want to sell one of each item in the machine, but when the server resets, or I reload customvendingsetup or monumentaddons, the items that were showing Sold Out are refilled. How do I fix this so that it only ever sells one item then stays sold out?
The settings in the machine are:

Max Stock: 1
Seconds Between Refills: 9999
Refill Amount: 0

The plugin is currently working as designed in this regard. It always restocks fully when the plugin loads. There is no simple "fix".

I will consider this a feature request.

It would be great if you could add that functionality.
Also, CustomVendingSetup_SalesData.data exists, but doesn't show any information, which is unfortunate.

Is there a way to label sale items? I want to sell notes with specific information, but the only way to destinguish between them is to have different prices.

Why did you mention CustomVendingSetup_SalesData.data? That file stores the record of purchases so that the plugin can track dynamic prices across restarts/reloads. I'm not aware of any use case for people to edit that file.

There is no way to label sales items today. I'll think about it for a future update but this will probably be low priority for me.