So my project has tools which can be bought only once by players, and hence is the need of searching all the clients for the tool. If the client has a tool, how can I make that client unique, like
local ToolOwner = client
something like that? And also, I need to check if the player has multiple tools in the same way. Can you please help me?

3 comments
Can't you loop through GetPlayers() and search through every player's backpack from the server?
By using a for iv in pairs loop get children
how to do that and also confirm the owner of tool, or parent of it?