By default the “Last Modified By” field is hidden in vTiger, however all the functionality and the actual field is there. In order to unhide it you will have modify the database.
We strongly recommend to backup vTiger files and database before doing any changes to code/database.
You will need to run the query below:
UPDATE vtiger_field SET presence=’0′, displaytype=’1′ WHERE fieldlabel=’Last Modified By’ AND columnname=’modifiedby’ AND tablename=’vtiger_crmentity’;
Note, this query will enable Last Modified By field for ALL the modules, if you wan’t to enable it for just one module you will have to add “AND tabid=’Tab ID goes here’”; You will have to lookup tabid for the specific module in vtiger_tab.