Does anyone know exactly when a PM license is consumed?

The knowledgebase says when someone is in PM or if a user does not have Production Management open but they are in a different module and the task has a work ticket tied to it, a Production Management User License will be used.  Any process integration that requires the Production Management program to be used will consume a user license.

Example:  A user is not in Production Management but they are in a Purchase Order with a Work Ticket tied to it, Master Console will show a PM User License being used while that Purchase Order is being accessed.

Looking for more clarification when in comes to SO Entry, Shipping Data Entry and IRP? Most sales orders have work tickets tied to them, so if shipping is invoicing a sales order with a Work ticket tied to it, does that count?  Also if running IRP reports since the demand draws from work order, will that count?  

Thank you.