Hashicorp Vault Licensing

Vault is licensed under the Mozilla Public License, version 2.0.

MPL v2 states [0]:

Q5: I want to use software which is available under the MPL. What do I have to do?

Nothing. Like all other free and open source software, software available under the MPL is available for anyone (including > individuals and companies) to use for any purpose. The MPL only creates obligations for you if you want to distribute the > software outside your organization.

Q6: I want to distribute software which is available under the MPL, either changed or unchanged, within my organization. What do I have to do?

Nothing. The right to private modification and distribution (and inside a company or organization counts as 'private') is > another right guaranteed by free and open source software licenses, including the MPL.

So redistribution (even a modified version) for sale or really any use is fair game.

[0]: MPL FAQ