The seat model does not fit agency work. You do not need a platform licence per client; you need a different list every month, for a different ICP, delivered under your own brand.
Why per-seat pricing hurts agencies
A seat is priced for a salesperson who uses it every day against one market. An agency uses it in bursts, against a new market each time. You end up paying for eleven idle months to cover the one you needed, multiplied by every client on the roster.
One balance, many projects
Credits work differently. One balance covers every client, spent only when a list is actually built. A quiet month costs nothing, and a heavy month costs exactly what it produced.
Bill list building as a line item, not an overhead. It is one of the few costs in an agency that maps cleanly to deliverables.
Pricing it into the retainer
Work out the cost per thousand for the sources that client needs, add your margin for the filter design and the QA pass, and put it on the invoice as its own line. Clients rarely object to a data cost they can see; they object to a vague research fee.
Delivering under your own brand
The file arrives as a plain CSV with no branding on it, so what you hand the client is your deliverable. Keep the search URL on file, and a refresh next quarter is a five-minute job you can charge for again.