Netsuite integration to FCCS issues with token expiring after 60 days

Summary:

My client has an integration with Netsuite to FCCS which runs fine for about 2 months, then the token appears to be become invalid.

Content (please ensure you mask any confidential information):

The integration is configured under Applications - configure connections - Netsuite.

The credentials from the Netsuite administrator have been added as the consumer key and token keys.

The Key type is Custom and the Connector is EPM Connector .

The integration produces an error after approximately 2 months where the log shows this error:
{"error" : {"code" : "INVALID_LOGIN_ATTEMPT", "message" : "Invalid login attempt."}}
ERROR [AIF]: EPMFDM-140336:Webservice call failure. HTTP error code: HTTP response Code:403