In ST03N, if you choose the standard transaction profile analysis view you'll get a full list of transactions, not organised by user:
You'll only be able to get it month by month and you'll have to merge the lists together separately in Excel or some other tool. If only 3 months data are recorded, then that's all the data you can get. If the system doesn't recorded it, you can get it afterwards! You can configure ST03N to keep data for longer. I have 12 months worth in my systems...
You could look at the transactions made available to users in their roles, but that only shows you what they could use, not what they have used. And it only shows you the current list, not taking into account any changes.
Steve.