It would be good if you would have posted this question in the correct sub-forum, Real-Time Alert Manager was definitely the wrong place.
The technical realisation depends on the tool you work with (PowerCenter, PowerCenter Express, IDQ...), but the general outline is this:
You source the data sorted by account ID and the date column in question. You can have the data sorted either from the source database (in case the source data are stored in a DBMS), or you can sort them in the mapping using a Sorter transformation.
Then you push the sorted data into an Aggregator transformation. Make sure that this Aggregator transformation groups by account ID. You can either use the LAST() function to retrieve the last record for each account ID, or you simply group by account ID without using any grouping function, then the Aggregator will always deliver the last record per input group (in your case, per account ID).
Finally you forward the output of the Aggregator to your target table.