When creating any commercial content that features a recognizable individual or individuals, a Model Release is used, which grants permission to the photographer and the right to use the model’s likeness under the conditions laid out in the release.
I use the standard releases from Shutterstock. Here are links to the releases that I use:
Model Release for Adult
Model Release for Minor
These are standard releases, and although I often submit my images to multiple agencies, it is common practice that only one release is required. Each agency will accept any standard release from another agency.