I have a collect a ton game where you collect tokens to win. But I want to make it that when the player connected the token it cannot be collected again and remember it when the player returns next time. The same thing is in Bee Swarm Simulator where you have hidden items you can collect one time. I have a little idea how to approach this but I am still kinda confused with the system. I would probably use datastore to save the variables? but I am not exactly sure.
Data Stores are the way to do this. You should research Data Stores, and learn the most effective way to use them.
For your situation you would be writing a value to a Data Store for whatever the player collected, and to determine if the player has collected the item you would use the value from the Data Store.