How to Memoize/Cache Lambda Function

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I came up with this solution, I don’t if it’s a proper implementation, please let me know if there is a better implementation.

import fetch from 'node-fetch';
const {API_TOKEN,USER_ID} = process.env;
let data = [];
let lastUpdate = 0;

exports.handler = async (event,context,callback) => {

	const fetchHotDeals = async () => {
		try{
			const activeCategoriesRes = await fetch('http://api.example.com/category/GetActiveCategories',{
			method: 'GET',
			headers: {'APIToken': API_TOKEN}
			});
			
			const activeCategoriesData = await activeCategoriesRes.json();
			const allCategories = activeCategoriesData.result;
			const subCategories = allCategories.filter(category => category.ParentCategoryId !== 0);
			const categoriesIdArray = subCategories.map(category => category.CategoryId);
			
			const productsNested = await Promise.all(categoriesIdArray.map( async categoryID => {
				const categoryProductsRes = await fetch(`http://api.example.com/Product/GetProductByCategory?CategoryID=${categoryID}&UserID=${USER_ID}`,{
					method: 'GET',
					headers: {'APIToken': API_TOKEN }
				});
				const categoryProductsData = await categoryProductsRes.json();
				return categoryProductsData.result;
			}))
			
			const productsList =  productsNested.flat();
			const hotDeals = productsList.filter(product => product.DiscountPercentage > 15 && product.SellingPrice > 50);

			return hotDeals;
				
		} catch (error) {
			callback(new Error("unable to generate hot deals"))
		}
	}

	const currentTime = new Date().getTime();

	if(data.length === 0 || (currentTime-lastUpdate > 3600000)){ /* 3600000 = 1hour */

		const hotDeals = await fetchHotDeals();
		data = [...hotDeals];
		lastUpdate = new Date().getTime();

		callback(null,{
			statusCode: 200,
			body: JSON.stringify(data)
		});

	} else {
		callback(null,{
			statusCode: 200,
			body: JSON.stringify(data)
		});
	}
	

}