Phone activation requires internet connection.
To use all the features, you need to activate the software. The "Activate" button will appear green in this case.
Connect the phone and you will be asked to activate the phone. You do not have to activate the device but you will not be able to read or write the device content.
Once activated you will be able to see the list of all activated phones for your license and also the number of remaining free slots.
Once you activate the phone you can not deactivate it. If you want to use more devices you have to purchase a new activation slot for a lower price.