Do you have to do these by a certain date, or when this time rolls around next year, will I be able to continue to lay flowers at the memorial and receive/give kisses to count toward the achievements? Thanks!

I don't think you have to do them by a certain date. I remember giving a kiss to the memorial in a month that was not February or March.

You can continue to lay flowers at the Memorial, they just don't restock in Seedlings. :)

Okie dokie :) Will they begin to restock again next year around this time?