Customer feedback indicates that there's a reliance on received e-mails to keep track of what they've approved through the customer portal. Looking into the experience, I noted that the 'Search Approvals', 'Approval Search' screen only offers the option to see approval tasks that were completed less than four weeks ago (Completed < 4 weeks).
I can't see any valid reason why the search would limit results to within a month. The present options only show users this limited range of data, with the requirement that an Approval Task number be entered to recall anything beyond 4 weeks - It's no wonder we have users, particularly in management positions, relying on e-mail to recall what they've approved.
Adding the option of greater than 4 weeks (> 4 weeks) or allowing users to select a date range would allow a greater selection of approvals for auditing.