When chips are manufactured there are process tests using test structures embedded in the pad ring and scribe area between the die images, as well as functional

When chips are manufactured there are process tests using test structures embedded in the pad ring and scribe area between the die images, as well as functional tests that are specific to the design. Risk production just means the "customer" will accept the parts from the fab without the parts being fully tested. In other words, the customer is accepting the "risk" of parts not working. When the fab settings and test flow are mature then the fab assumes responsibility for parts that do not pass the testing.