There's conflicting info on the website and in the preview contract. Conflicts highlighted by me in bold.

Pricing table on https://hise.dev/#license says it's HISE-based:

Indie: less than 50.000 € annual revenue made with HISE-based products
Pro: more than 50.000 € annual revenue made with HISE-based products

The preview contract first says it's company-wide revenue, regardless of HISE:

Section C.2

"The licensing fee shall be payable monthly and be measured in terms of the total annual revenue generated by the Customer, regardless of whether this revenue is related to the Software or not."

Then Annex 2 goes back to HISE-based:

Annex 2 (pricing scheme)

The total net revenue is the sum of all revenues that is being generated using products based on HISE.

So the website and the pricing annex in the contract agree on HISE-based revenue, but Section C.2 of the contract seems to say it's the total revenue generated by the customer, whether from HISE products or not.