Chiar si in romana se foloseste "key accounts", daca e vorba de acelasi lucru - ai putea sa dai mai mult context.

As Key Account Manager the main responsibilities are:
- Maintain and develop new business relationship with the existing partners and customers.
http://www.ejobs.ro/user/locuri-de-munca/key-account-manager...

key account = A wholesaler's or manufacturer's primary customer that provides the majority of sales volume.
http://www.foodsfortrade.com/definitions/index.php/letter/K