Question about Licensing on the Penetrator

I have a question regarding licensing. I understand that if I buy, for example, a single IP license then there is technically no limit how many IPs I can scan but I can only scan a single IP at a time. Does that mean that if I want to scan more, I have to wait for the previous scan to finish and manually initiate the next scan? Or is there any way to schedule more IPs to be scanned automatically (not concurrently but in succession without user intervention)?

Correct.
Even with 1 IP you can put in 1000 IPs and it will do queue and do 1 at a time.
If you have a 4 IP it will do 4 IPs at a time.
So it is like a car with the horse power you pay for.

Also, is there an average scan duration per IP? Or does it vary a lot depending on the type of host?

It is made intelligent to be as fast as possible.

Example let say you put in a /24 class
and only 30 Ips are online reposnding then the other IPs that are not running will be shown as offline so it wont scan those.
And if you scan an IP without a web server it wont launch web attacks.
But if you scan another IP with Web Server, Ftp Server, Mail server
it launch those checks.

It can be in general anywhere from 10 min per scan to a few hours depending on how much it finds.

You can also do report branding so if you offer it as a service to your customer you can add your company logo in the reports.