This design presents a modal window for upgrading to a Plus subscription tier, featuring a dark theme with a sleek and modern aesthetic. It includes billing options, payment details, and add-ons section, emphasizing the monetary saving of paying annually over monthly. The add-ons section specifically highlights an AI Assistant service, suggesting advanced features available for integration. Clear visual hierarchy is achieved through the use of contrasting colors and distinctive sections, with a strong call-to-action button for completing the upgrade process.