Your license is tied to your account. You can move your license to another PC by disconnecting your previous PC. (In case you want entirely new build of server)
But for upgrade path, please keep all your boot drive and pool drives. You can change the CPU, motherboard, RAM, GPU, except drives.
As right now, HexOS doesn't recognize existing pool and configs, but hopefully in v1.0, you will be able to import existing pool so you can change your boot drive.
If you want to increase your storage, you can expand by adding dditional drive to your pool. Or if you want upgrade/replacing drives, you can pull out the ONE drive and put in the new drive and let the OS rebuild your data, wait until it finished and then do it again to another drive (one by one).
There will be a documentation that will explain everything and step-by-step to do it.