Is it possible to set different expiration time for same event in different DRL files ?

Issue

• Is it possible to set different expiration time (i.e. setting separate values for @expires on the events) for same event in different DRL files ?
  The scenario is when there are separate DRL files where the constituent rules are operating on the same facts (i.e. the structure of the facts/events are the same).
• In case of sliding windows how does the events set with expiration time behave ? If there exists a sliding window of 10sec then the facts(events) needs to be in memory all that time in order to trigger the rules. In such a scenario does it mean that older facts (according to the rules higher sliding window) will be removed automatically from memory?