in a process, Pct_Usage will not be available in any other process (except an immediately following process if Make Persistent is enabled).

However, you can save the derived field definition in the same way that you would save any other query. You can store the derived field definition in the Stored Derived Fields list and give it a name (for example, Pct_of_limit_used). Later, if you want to use the same derived field in another process in the same or a different flowchart, you can select Pct_of_limit_used from the Stored Derived Fields list and insert the stored derived expression, rather than reconstructing it from scratch.