You can install 8.7i. There's no 'activation' involved in this process.
But it would be most unusual and highly discouraged.
Like buying a Dodge Viper and deciding to cruise the streets on your tricycle... okay maybe not tricycle, but certainly a vehicle not as fast as the one you're entitled to use.
Because the PC's applicaiton is designed to controll some machines and need to work 24 hrs. My customer do not like " change", change means risk.
So he want to use 8.7,do not upgrade to 8.8, and the pc have no internet
And the pc have no internet, so virus pattan will not update, he just install the same anti-virus App to prevent USB virus...
If I install VirusScan Enterprise 8.7 , will I key in something like"serial number" or "license key" to verify?
to my best knowledge VirusScan is not designed to detect viruses when USB drives are plugged in (on the other hand it can scan USB drives after it has been plugged in and operable).
So you might want to disable autorun feature for plug and play devices and also disable autorun in Windows local policy...
Does this PC reachable from internal company network (because if yes it is as vulnerable as being exposed to internet)? If yes, and if you have central AV management (ePO), you could use the signature update from ePO repository...