Does a sap listener and listener notification must be in enabled state ,when the idoc is sent from the source.

if we enable them after the idocs are sent will we get the transactions at wm end.

Yes, both of them need to be enabled to receive the documents.

If they are not:

• the SAP System does not know where to send them (Program-ID, Destination in SAP)

• the SAP Adapter does not know which service should take care of the processing

Listener takes care of the first option, otherwise the idoc will never arrive on IS side.
Listener Notification takes care of the second option, otherwise the idoc will show up under Transactions in the SAP Adapter as Rollbacked.

Hope this helps.