You can only allow third parties to install your app on their devices for testing if you have written approval from Apple.
You can only use a limited number of devices that you/your company own for testing.
Your license to use Xcode, the SDKs, and release software for iOS can be revoked at any time: "Apple reserves the right to revoke, disable or suspend any Provisioning Profiles or any access to the device deployment and provisioning features of the Apple Software and Services at any time, in its sole discretion. By way of example, Apple may do this if Apple has reason to believe that Apple IDs were fraudulently obtained, that an unreasonable number of devices have been entered into the Apple Software, and/or that the Services are being used in a fraudulent, suspicious, or improper manner."