Hi,
SM19 & SM20 is the best option to check the 1 week ago used t-codes by user but before that SM19 should be in active for that user and you will get the audit log in SM20. Usually in support projects SM19 will be enabled for all the users.
from STAD t-code will get only the data for (24 hrs) and if there is any custom t-code for STAD we will get the data from months ago.
currently we are using custom t-code which will get the data for minimum 3 months ago.
Regards,
Babu