As I see Pega use Hazelcast IMDG Enterprise but I am wondering that Can we use Hazelcast IMDG Enterprise HD version? Because pega marketing outbound campaigns work with large amount of data and Hazelcast IMDG Enterprise HD provides High-Density (HD) Memory Store and Hot Restart Persistence features in addition to Hazelcast IMDG Enterprise.
As of now, Hazelcast is embedded in the Pega platform. You cannot simply switch to different edition. However, Pega is in the process of externalizing Hazelcast to a service independent of Pega core platform, but that will be in the future releases. Hope this helps!