This tech doc answers this question...when upgrade from 8.1/8.5/8.6 to 8.7, do I need new license keys?
Release : 8.7
Component : CA 2E
You don't need new license keys if you still have your 8.1 keys handy as you would need to re-apply the keys
https://techdocs.broadcom.com/us/en/ca-enterprise-software/it-operations-management/ca-2e/8-7/upgrading/upgrading-the-software.html
(see "Running the Licensing Routines")
Of course, if you can't find the existing keys anymore then you would need to require one from CA License team