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
