If customers know what they’re buying, and unsubscribing is convenient, then I see no ethical problem with selling limited-term licenses—but as you mentioned, s

If customers know what they’re buying, and unsubscribing is convenient, then I see no ethical problem with selling limited-term licenses—but as you mentioned, some potential customers might choose not to buy. Depending on the purpose of the software, it might be reasonable to require a current subscription only to enter new data or to perform new calculations, while allowing customers to view and export their existing data in perpetuity.