Hi Andrei
Based on the above information, it seems you purchased an upgrade for CCX 8.5 Standard to CCX 9 Premium for 20 seats which is denoted the CCX85-90U-S-P-S1.
You need to Register the PAK on https://tools.cisco.com/SWIFT/LicensingUI/Home
License file will be emailed to you.
Please check the Licensing FAQ below for more details:
https://www.cisco.com/web/fw/tools/swift/xui/PDF/Cisco_Licensing_FAQ_-_June_2011.pdf
Regards
Inderpal Singh