Operations Manager are free to upgrade as long as they are within the same version, for example 2.0, 2.01, 2.03... 2.1, 2.3 (minor upgrade within the same main version)
however since 2.x -> 8.x is a version change (major upgrade) it will require a new license and the 2.x license will not work under 8.x
If you wish to pursue a new 8.x license you may use the Upgrade Tool and
work through your account team http://www.cisco.com/upgrade
