If we select ‘Created and every time edited to meet the criteria’ whenever we create a record or edit a record if the criteria of the workflow rule meets then it will trigger every time.
If we select ‘Created and edited to subsequently meet the criteria’ – whenever we create the record that meets criteria so that workflow will fire and while editing the record again criteria meets workflow won’t fire (meeting the criteria to meeting the criteria).
When we create the record, if the record criteria don’t meet then the workflow will not fire. In the dame way if criteria meet while editing the record then the workflow will fire.
Conclusion: Previous state of record should be not meeting criteria and current state of record should be meeting the criteria then only in current state workflow will fire.