Assets and Targets defined
Pentest-Tools.com defines an Asset as the network host being scanned (e.g. hostname, IP address). The Asset is your main licensing limitation. 
An Asset gets broken down into one or more Targets, depending on its type.
A Target is the specific URL or IP address that our tools run scans on. 
Let’s take an example so it’s easy to make the difference:
The Asset example.com has two Targets:
By contrast, the following are individual Assets:
What about scanning IP ranges?
You can also scan IP ranges but they are expanded into individual Assets. For instance, scanning the IP range 8.8.8.1-100 creates 100 distinct Assets. Find out more on how to scan an IP range.
FAQ
Is the maximum number of Scannable Assets applied monthly or yearly?
The limit applies per 30-day scan cycle. Each subscription period (monthly or yearly) is divided into scan cycles of 30 days. At the end of each cycle, the Scannable Assets counter resets to 0.
What is a scan cycle?
A scan cycle is the 30-day period that begins when your subscription is activated. For monthly subscriptions, the scan cycle matches the billing cycle. For yearly subscriptions, there are 12 consecutive scan cycles, and your scannable assets reset at the start of each one.
How do you count Assets and Targets against subscription limits?
We only count Assets toward your plan limits. An Asset is defined as the subdomain, hostname, domain name, or IP address of the scanned system, network, or web application.
All URLs within the same web application (under the same domain name) count as a single Asset. The exception is subdomains, which are counted separately.
How many times can I scan an Asset?
Once an Asset is marked as scanned (you can track this in the Scanned asset section), you can rescan it as many times as you want within the same scan cycle. Subscription limits only apply to the number of unique Assets you can scan during that billing cycle.