FortiSandbox Cloud Question

We have a FGT-100D and I was just going through some security logs, and noticed a majority of my files which are sent to FortiSandbox are in a pending state. Upon further inspection I noticed that I have a free FortiSandbox license which only allows for 10 submissions per day which seems awfully low for any network.

How does one increase the amount of files allowed to be sent to FortiSandbox?