what does it mean when a corporate client asks to be able to use photos "in house". Does that mean, internally for the own reference only? Or does that mean, post on their own websites, use in their own corporate brochures, etc.
Your best bet is to just ask them what specific uses they need. But my guess would be they want to use them internally. The "Internal Company (PICO)" Plus Pack is probably a good license definition of what they're asking for:
"Use in any media intended for internal business purposes including internal presentation, newsletter, brochure, intranet and video. Applies to a specified end user."
This would require a much lower fee then if they wanted to use the images for advertising purposes on their external public website or in brochures distributed to clients.