Dormant customers= Active customers but hasn’t done any sales transaction for past few months or for more than 1 year, as defined by client.
Browsing the customer record, we can see the list of sales done under them, as in below:

To identify such customers who hasn’t done any sales transaction for past 1 year, we can use a customer search with DATE OF LAST SALE ( Standard ) field in criteria, provided the customer is ACTIVE.
