Whether you need a label depends on a lot of things, and, for a full understanding, it's best to read the FDA guide, or reach out to us.
It is always a good idea to be clear and honest with your customers, and one way of doing that is to provide nutrition facts. You are never prohibited from including nutrition facts on your packaging. However, there are certain foods and businesses that are exempt and others that MUST provide nutrition facts. For example, fresh fruit and vegetables don't require nutrition facts. Foods with nutrient content claims (e.g. "low-fat") must include nutrition facts.
More broadly, the size of your business dictates whether or not you need nutrition facts on your packaging. Businesses that sell $50,000 or less of food items or $500,000 or less of food and non-food combined are generally exempt. Businesses with fewer than 10 full-time employees and less than 10,000 units sold annually are also exempt. After crossing any of these thresholds, there is a leniency period of 18 months after which the business has to comply. More details can be found on our blog post covering the topic :)