Rocket Validator looks for accesibility violations on your pages using the axe-core accessibility engine, hosted on our own servers and integrated into our web crawler. You don't need to buy an additional license, everything's already included in your Pro account at Rocket Validator.
A11Y check: ARIA attributes must conform to valid values
Accessibility rule: ARIA attributes (i.e. starting with aria-) must contain valid values. These values must be spelled correctly and correspond to values that make sense for a particular attribute in order to perform the intended accessibility function.