Expiring Maintenance Job Series report is used to keep track of 'Custom series' jobs.
You can specify site/account customer, date range and search.

The coloured records indicate series that has expired i.e. no future maintenance jobs.
The white records indicate maintenance series expiring within specified date range i.e. the last job in maintenance series falls in that date range.

You can find this report in the main menu under Report - Maintenance report