As noted by bob fitz and by arnelgp, all you need is an indicator in the record. There is an old rule here: If you know you are eventually going to ask a question with Access, make sure ahead of time that the answer will be available in the record. SO you get to pick how you do it.
1. bob fitz's answer: Add a date field to the record
2. arnelgp's answer: Add a "finished" flag to the record
3. my answer: EITHER 1 or 2 (don't need both) OR take advantage of an existing date field or other information already in the record that implies what it is that you need to make the decision.
When you do have a "metric" (a way to identify the records to be archived), do it in four steps. FIRST, backup the database as a precaution. SECOND, export the records identified by the metric. THIRD, delete the records you just exported. FOURTH, verify by inspection that it did what you wanted. If it succeeds, you can discard the backup. If not, you have a way to start over again with no data loss.i