The SPDocKit Service is a Windows Service created by SPDocKit used to execute automatic jobs on a schedule. The automatic jobs the service executes are creating snapshots, sending of subscription and alerts, index reorganization, data retention and executing and sending of queries and rules.
If the service is not configured, you can still execute these actions manually, except for the index reorganization job.
Yes, you can do that via the SPDocKit Configuration wizard by navigating to: File > Configuration > Configure. The account used should be an Active Directory account with the necessary privileges granted.
Do not use your SharePoint databases as the database for SPDocKit. When configuring SPDocKit, you should always create a new database that is dedicated for SPDocKit.
Note: If there is an existing SPDocKit database you can connect to it.
Unfortunately, you can't use local system account as the SPDocKit Service account. The service account needs to have specific rights which can't be given to a local system account. See the user permission requirements.
Unfortunately, the SPDocKit Service can be used on a SharePoint server only.