If you would like to run CUE in an IOS XE Service Container, you will need to increase RAM and Flash to 8GB and include a hard disk too.
If you are using full IVR functionality in CUE, then you will need to purchase CUE-IVR session licenses (under L-CME-CUE, or in an ISR order).
Simple CUE AutoAttendant functionality doesn't currently require a license, but may require a minimum number of voicemail licenses in future releases.
Alternatively, if your call handling requirements are relatively straight forward, consider using the CME Basic ACD script. This does not require additional hardware, or licenses.