Rainlendar is a customizable desktop calendar application for Windows, macOS, and Linux that displays events and tasks on your desktop. It comes in two main editions: Rainlendar Lite (free) and Rainlendar Pro (paid). The Pro edition unlocks features like calendar syncing (CalDAV, Google Calendar), task and event alarms, network/shared calendars, and more advanced customization.

"r2lic" likely refers to a license file or identifier used by Rainlendar Pro. Rainlendar Pro uses license keys to unlock the paid features; when you purchase a Pro license you receive a key (a string you enter in the app) and sometimes a small license file or token that the program recognizes. Users often see filenames or internal identifiers such as r2lic, rainlendar.license, or similar when the application stores licensing information locally.