To create a new API key for Open API, go to Subscriptions > Services > API Maintenance.

After that, Click on the Add New button to set up a new API key. 

After that, users must maintain the title of the API along with the API Type and enabling the API modules as well. Once all that is done, you must select which company has access to the API. 

Within the same company, you may select which branch / department / project / entitlement group is / can be accessed by the API. Once done, click on the Save button at the top right corner to save the changes made.