How to limit how often a user can update a mysql value to a database

I have a field on my website, which updates a value in my mysql database. I want to make it so the user can only update the value every 3 days. How would I go about doing this?

Here is the code that I have written so far:

<?php
        if(isset($_POST['Update'])){
          $UpdateHWID = $_POST['HWID'];

          $sql = $con->query("UPDATE users SET HWID = '{$UpdateHWID}' where UserID = $User");

          echo "HWID Updated Successfully!";
        }
?>

Answer

Create new row into db (last_update) type= data

//return to sql last_update (select db ...)

$current_Data = date ('Y-m-d');
$current_Data_time = strtotime ($current_Data); //convert data to time
$last_update_p3 = strtotime ("+3day", strtotime($last_update));
$last_update_p3 = strtotime ($last_update_p3);//convert data to time

if($current_Data_time <=$last_update_p3)
{
 $sql = $con->query("UPDATE users SET HWID = '{$UpdateHWID}' , last_update='{$current_Data}'  where UserID = $User");
//update last data with current date 
}
else
{
//It has not gone three days 
}