The phrase "to maintain the account" means to take care of or keep up with the account, keeping it updated, organized, and fulfilling any necessary requirements. Full definition
Perform any combination of routine calculating, posting, and verifying duties to obtain primary financial data for use in maintaining accounting records. (onetonline.org)
You will be responsible for compiling and maintaining accounts payable records. (ziprecruiter.com)
Used innovative sales techniques to acquire & maintain accounts with large employers. (resumemycareer.com)