Each airline has different rules

To request mileage credit for Continental flights flown in the last six months, provide the required information below and then click Continue.

For a 25 USD fee, you can request retroactive mileage credit for your Continental Airlines, Continental Express and Copa Airlines flight activity during the six months prior to your enrollment in the OnePass program.

http://www.continental.com/onepass/o...4E1D58A874DA87