You would probably have to make use of eval(), but, "If eval() is the answer, you're probably asking the wrong question." More secure would be to just embed some sort of place-holder in there, then replace it via str_replace() or sprintf(), or printf(). E.g.:
$textFromDB = "blah blah blah _CURRENT_MONTH_ blah blah blah";
echo str_replace('_CURRENT_MONTH_', date('F'), $textFromDB);