This may be a bug.
My Rainlendar Pro is used to sync Google Calendar across my windows, android and Linux machines. The problem exists only on my Windows machine...
I will occasionally find that Rainlendar has (without my input) advanced by several years.
For example: If I input a new appointment for May 17, and go looking for it on May 17, 2014, I will not find it on that day, but on May 17, 2017! This is an actual occurrence. I double check the Rainlendar calendar window and it shows that it has advanced to 2017. I have checked the local machine date and it has the correct date, so I do not believe that Rainlendar is getting an incorrect date from the Windows OS.
This recurring event is an annoyance in an otherwise wonderful program and I'm glad I bought it.