using last. for observations with multiple

[ash]

I have a dataset of patient records with multiple rows per visit date and multiple visit dates.  I used first. to create a cumulative sum of costs across the rows for a single date and a record counter.  Now I want to drop all rows except the one with my cumulative sum (the highest counter) for each patient and visit date.  

Example data:

idno	visitdate	pay	cumupay	counter
1	5/5/2019	5	5	1
1	5/5/2019	5	10	2
1	10/31/2019	5	5	1
1	12/25/2019	5	5	1
1	12/25/2019	5	10	2
1	12/25/2019	5	15	3
2	7/4/2019	7	7	1
2	7/4/2019	7	14	2
3	9/2/2019	9	9	1

[novinosrin · Accepted solution]

data want;
 set have;
 by idno visitdate;
 if last.visitdate;
run;

[ash]

Thank you. That's probably the only combo I hadn't tried, since I thought that would have kept only the last visitdate (from my example, I would think that would have kept: ID = 1 and only the last row of the last visitdate (12/25/2019).