The calendar should allow selecting multiple dates based on the chosen package (dates match the package duration / number of sessions). Calendar access should be valid only 1–2 months after purchase; after payment the user receives a Calendar ID to book preferred dates within validity. A GTalk ID valid per package should also be provided (12-session → 12 sessions, etc.).

Key requirements: multiple date selection; based on package; Calendar ID expires 1–2 months after purchase; enabled only after successful payment; GTalk ID valid per session count.