Most sellers use the name of their Amazon account, however, it does not have to be a registered business name. It will only be displayed on the FBA Shipping Label so it can be changed later if you wish to change it.
To change your business name in InventoryLab for the shipping label, click on your name in the upper right and corner of InventoryLab and select Settings from the drop down menu
You should be on the Shipping Information tab automatically. Click on the Edit button
Then, simply type in a new business name and click Save