Hard Disk Monitoring

I have been using HDS for quite some time with a Pro licence. I wish to use it on a USB drive to test other computers. Do I need a second licence for the USB drive or does the Pro licence include USB

If you want to SWITCH your installed Hard Disk Sentinel Pro license to the Portable - then it is absolutely possible any time, no need to have a second license.

You'd only need a second (different) license for Hard Disk Sentinel Pro Portable version if you'd prefer to keep the existing installed version and (in addition) to use Pro Portable version too. Then you'd need separate license for both.

Both the Installed and Portable versions are (in terms of licensing) same: they are both Professional version: they have 100% same functions, features.

The only difference is how the software deployed (installed OR started from a removable device, eg. pendrive/CD) and started (automaticaly on startup OR manually).

So generally, if you have ONE single (non-Family) license for Hard Disk Sentinel Professional, you can decide if you prefer to use
- with the Installed version (to get real-time protection)
OR
- with the Portable version (to use by a pendrive, without installation to diagnose / fix issues)

If you'd prefer to use both the installed and Portable versions, you'd need to have different licenses - or a Pro Family license: the Family license grants use on multiple systems and/or multiple pendrives.
For example if you'd have a Hard Disk Sentinel Pro Family license, you can use on up to 5 computers / pendrives (in any combination), for example
- install on 4 computers and use the Portable on 1 pendrive
- install on 3 computers and use the Portable on 2 pendrives
- install on 2 computers and use the Portable on 3 pendrives
and so.

The page
https://www.hdsentinel.com/hard_disk_se ... sional.php
may also give additional details.

I already have the family licence on 4 computers, when i tried to activate the portable version is says i need a separate licence for the USB version so i am a little confused.

No....
I double verified and I'm afraid you have a SINGLE PC license.

This is why you see the license-conflict warning message.
Attempting to use it on multiple computers should be avoided as it may result in blocking of the license.

I sent you an e-mail about the license information and an economic way to upgrade to Pro Family license, which can be really used on 5 computer (or 4 computers plus the pendrive).