From The Document Foundation Wiki
    < Faq‎ | Calc

    How to insert a variable date into a cell

    Insert a function into the cell, following these instructions:

    1. Select the desired cell.
    2. Go to Insert ▸ Function.
    3. In the Categories list, choose Date and time.
    4. Click on TODAY to get the current date or NOW if you also want to write the hour.
    5. Click on Next.
    6. Click on OK.

    Since version 3.6 of LibreOffice you can also insert the date as a field:

    1. The cell must be in the Edit in place state (double click in the cell)
    2. Right click, choose Insert field ▸ Date

    If you do not want the date to be updated, use the keyboard as follows:

    • Ctrl + ; to insert the date.
    • Ctrl + ⇧ Shift + ; to insert the time.