Hello Kiran,
This is a good question! I would distinguish two aspects:
- From a technical perspective, a NetWeaver PO system is a NetWeaver 7.4 system with usage types PI (incl. PI-AF, PI-AEX and ESR) and BPM (incl. CE-APPS and BRM) installed. In you case, with a NetWeaver 7.4 system with PI usage type installed, it is very simple to switch to PO: you just need to add the BPM usage type.
This can be done very easily with Solution Manager Maintenance Optimizer, as documented in the Maintenance Transaction with Installation of an Enhancement Package SAP Help page (which includes installation of usage types).
As Dimitri mentioned, in the case you have a dual-stack NetWeaver system, you will need to migrate your system to a Java only stack first.
- From a licensing perspective, NetWeaver PO is considered as a bundled product and requires a specific license. It can be converted from the license you already acquired for PI.
I recommend you the SCN blog article Upgrade Options to the Latest Process Integration or Process Orchestration which explains this very well!
Regards, Stephane