Adobe Experience Manager is one of Adobe's largest enterprise line items, and one of the hardest to read. AEM Sites and AEM Assets are priced through packages and capacity units that bundle software, environments and a notional usage allowance into a single figure that resists comparison.
The trap is that capacity is sold ahead of need. The packaging assumes a scale of sites, authors, assets and traffic that few deployments reach in the early years, so you commit to capacity that sits unused while the meter runs. Add the as a Cloud Service environments and the number climbs again.
AEM is also where renewal uplift does the most damage, because the base is so large that a small percentage is a big absolute cost. Without a clean read of what you actually consume, the uplift compounds on top of capacity you were never using.