hi Jinglei,

If you upgraded IOS XR sw and now you need to have a license, you can follow the steps on the following link:

http://www.cisco.com/en/US/docs/routers/asr9000/software/asr9k_r4.2/system_management/configuration/guide/b_sysman_cg42asr9k_chapter_0101.html#concept_DD99F4E7E74044A2BC53D256AC372511

The summary steps CLI are:

SUMMARY STEPS

      1.    admin

      2.    show license udi

      3.    http://www.cisco.com/go/license (to get the license)

      4.    Copy the license to your TFTP server.

      5.    admin

      6.    license add license-name [ sdr sdr-name ]

      7.    license license-name location { all | node-id }

      8.    exit

Let us know if that meets your requirements or if you have a different situation.

regards,

David