The article discusses designing annuities with flexible benefits that can change based on how long people live. This means less strict guarantees compared to regular annuities. The annuitant may face lower premiums but also the risk of reduced benefits if people live longer. By using periodic fees instead of upfront costs, the annuity can be adjusted after purchase. The researchers looked at different ways to link benefits to how long people live and found that periodic fees can be calculated using a discount factor. This approach offers more flexibility for annuity holders and could make these products more appealing in the market.