Using your FileFactory Premium account across multiple computers or devices should not be a problem.
However you can only use your FileFactory Premium account on one particular PC or device at a time. We will automatically sign you out any active sessions on your other PC or device, if you sign in on a new PC or device.
For example if you are signed in to your FileFactory account at 'home', then you go to 'work' and sign in there, you will probably receive an "IP address mismatch" error. You'll then be signed out of both accounts, and will need to sign in again.
Once you've signed in again at 'work', there should be no more problems for that session.