CJA - licensing questions

CJA is fundamentally built on top of AEP. It does not collect data on its own; rather, it functions as the reporting and analysis layer that directly consumes datasets stored in the AEP Data Lake
Hence CJA cannot be used without AEP .  
However if you are only capturing Web data you can Use AA which is same workspace of analysis but with some web-centric twist.

AEP comes as part of the Bundled Services that you cannot license CJA without. But you also cannot license AEP separately.

The AEP data lake receives the data that you ingest through batches or streaming. CJA connects to the data lake through its connections, and copies/loads the selected AEP datasets into its columnar reporting store, the engine behind Data Views and Analysis Workspace.