APM Licensing

Please disregard question below, I understand how licensing works but it doesn't make sense to me why is that CCU is lower than User Session even we know that:

1user = 1 session license but this 1 user can consume 2 or more CCU due to resources like (Portal,Webtoplink, Network Access, AppTunnel etc.)

https://support.f5.com/content/kb/en-us/products/big-ip_apm/manuals/product/f5-apm-operations-guide/_jcr_content/pdfAttach/download/file.res/f5-apm-operations-guide.pdf

My question is how CCU licensing works is it:

1 CCU per Portal Access means (1 for portal1.com + 1 for portal2.com ) or 1 for all (portal1.com and portal2.com)?