When you fill in the project form, let the voice actor know:
How, where, and for how long the voice recording will be used.
How. For example: will the voice recording be used internally (within your company as a training video), for non-profit, educational purposes, or externally (publicly) as promo material in a presentation, or as an advertisement?
For how long. For example: will the voice recording be used only once? Several times? Consistently for a year? Do you want it to be used indefinitely? You may then have to negotiate an in-perpetuity buyout with the actor.
Where. For example: will the voice recording be used on television or radio? On a video-streaming site? Embedded as an explainer on a homepage? What size is the audience likely to be? Give as accurate a ‘guesstimate’ as you can.