create table user_activity(id int(11) not null auto_increment,
                           month date,name varchar(15),
                           activity enum('A','I'),primary key(id) );

 insert into user_activity (month,name,activity) values('2019-01-01','alpha','A');

 insert into user_activity (month,name,activity) values('2019-02-01','alpha','I');

 insert into user_activity (month,name,activity) values('2019-03-01','alpha','A');

 insert into user_activity (month,name,activity) values('2019-01-01','beta','A');

  insert into user_activity (month,name,activity) values('2019-02-01','beta','I');

select * from user_activity

| id |      month |  name | activity |
|----|------------|-------|----------|
|  1 | 2019-01-01 | alpha |        A |
|  2 | 2019-02-01 | alpha |        I |
|  3 | 2019-03-01 | alpha |        A |
|  4 | 2019-01-01 |  beta |        A |
|  5 | 2019-02-01 |  beta |        I |

select max(month),name,activity
from user_activity
where activity='A'
group by name

| max(month) |  name | activity |
|------------|-------|----------|
| 2019-03-01 | alpha |        A |
| 2019-01-01 |  beta |        A |