How GTM Agencies Manage Clay Access, Credit Costs, and Pricing Models for Client Work

I’m curious how GTM agencies typically handle Clay access and credit costs for client work. Do most agencies have clients subscribe to Clay directly and grant the agency access to their workspace? That seems like the cleanest model: the client owns and pays for Clay credits/data providers, while the agency separately charges for strategy, list building, enrichment, and workflow management. Or do agencies usually run work inside their own Clay account and build credit usage into their pricing? If you operate an agency or hire one, I’d also be interested in seeing real-world pricing structures—monthly retainers, per-record pricing, setup fees, usage allowances, or other models that have worked well.