Startups offering lifetime deals is a very good strategy to gain initial traction. This can help gain a large amount of capital which can then be re-invested to further develop the product. A business can then turn these customers acquired through these lifetime deals into affiliates.
Customers who purchase lifetime deals can offer feedback to the developer. Then, with these new features in place, one can now upsell an upgrade to access these new features directly to the consumer rather than through a platform like AppSumo.