Get today's date (& time) and apply them as maximum date.
Calendar c = Calendar.getInstance();
c.set(2017, 0, 1);//Year,Mounth -1,Day
your_date_picker.setMaxDate(c.getTimeInMillis());
ALSO WE MAY DO THIS (check this Stackoverflow answer for System.currentTimeMillis() vs Calendar method)
long now = System.currentTimeMillis() - 1000;
dp_time.setMinDate(now);
dp_time.setMaxDate(now+(1000*60*60*24*7)); //After 7 Days from Now