If you have your iPad with you then the easiest way to assign a license is just to start the event on your iPad. As soon as the event is started it will assign a license to that specific event on that specific device (iPad).
Viewing all your licenses
If you do not have your iPad on hand or would just like to check which licenses are assigned to which events/devices then you can go to the "Licenses" tab on your dashboard. The "Licenses" tab will show you all the licenses you have on your account; which ones are assigned to which event/device and which ones are available.
Assigning a license remotely
If you need to assign one of your available licenses to an event remotely, or if you mistakenly revoked a license from the dashboard, or someone deactivated the license for your live event to start another event then you can reassign the license by going to the "Licenses" tab.
Depending on your package you will either see "Account Licenses" (for monthly and yearly packages) or "Event Licenses" (these are specific to a event) or both.
For Account Licenses:
To assign the license you just click the "Assign" button next to the available license and then choose from the drop downs, the name of the event and the device you want to use - see image below.
For Event Licenses:
To assign an event license you also just click the "Assign" button but it will only give you an option to choose the device you want to use, as this license is for this event specifically.
Then your live event will automatically have the license assigned to it, no need to refresh the event.
This will only work if the event is still open and running on the iPad with an internet connection.
If the event has been exited after having its licence revoked (and before having one assigned using the above instructions), it will refresh and lose its licence. You will need to manually refresh the event on the iPad in this case.