What type of data is being rolled up? Dates? Numbers? Strings? Knowing this will help us know how to find that last value.

It would also be helpful to know if you want a value from the last record in the list of linked records, or the last record based on a field value in the linked table. They are not always the same.

The more information you can provide, the better. There are various ways of obtaining data from the “last” record. In some situations, the information can be obtained in a single rollup field. In other situations, you need a system of rollup fields where you pass information back and forth between the two tables. Still other situations call for a script.