At the moment it is possible to create only 3 units in one account of the basic version of the application as well as in Premium version, unfortunately.
You can see the number of units created/left to create in Dashboard tab - Info - Units.
You can find out the price and subscribe to the Premium version in your account in the User Settings - Subscription Management. At the moment you can subscribe to the Premium version via the Android platform and it will be valid when using your account on all your other devices.
Could you please describe a bit more your business so that we cold have better understanding of our users needs?
We recommend you to try our professional business solution Wialon https://gurtam.com/en/wialon which seems quite useful for your business needs.