How can I change from true to false?

How can I make the discord bot change my premium: true to premium: false after the set date package expires.

This is the initial code:

const member = message.author.id;
const premium = await Premium.findOne({ member: member });
const plan = 'month'

const expirationTime = 2592000
let currentTime = Date.now();

if(!premium) {
   const newPremium = new Premium({
   member: member,
   premium: true,
   redeemedBy: message.author,
   createdAt: new Date(currentTime),
   expiresAt: new Date(currentTime+(expirationTime * 1000)),
   plan: plan
});

This is the established database:

const mongoose = require('mongoose');

const CreatePremium = mongoose.Schema({
    member: String,
    premium: {
        type: Boolean,
        default: false
    },
    redeemedBy: Array,
    createdAt: String,
    expiresAt: String,
    plan: String
});

module.exports = mongoose.model('PremiumU', CreatePremium);