If I understand correctly, you're wanting to implement Keygen into an on-premise infra app that you would be selling? If so, that's definitely the sort of thing Keygen was designed for, even giving you the ability to lock down licenses to specific machines.

Still trying to figure pricing/costs as the beta progresses (let me know if you'd like an invite), but the hosted SaaS will likely start out at ~$29/mo for the smallest plan (single product), increasing with product/user/license volume. On-premise plans (self-hosted) will be solely based on volume and required support levels.