Created the "bought item" controller

controller/boughtItem.js

@@ -0,0 +1,9 @@
+const {mongo} = require('mongoose');
+const BoughtItem = require('../models/BoughtItem');
+
+// Checks if the user owns a specific addon
+module.exports.ownsItem = async (user_id, addon_id) => {
+    if (!mongo.ObjectId.isValid(user_id)) return;
+    if (!mongo.ObjectId.isValid(addon_id)) return;
+    return await BoughtItem.findOne({user_id, addon_id}).exec() !== null;
+}