No Jailbreaking

Unfortunately it is not possible.

Without a paid developer account, you do not have the necessary certificates to prepare your devices for the application installation.

The term used in the documentation is " Code Signing which essentially allows:

  

1) Running Your App on Device Thru Xcode
  2) Testing Your Submission Build with Ad Hoc distribution
  3) Submitting Your App to the App Store
  4) Creating and Installing an Enterprise build for In-House distribution

What translated:

  

1) Run the application on the device through Xcode
  2) Test the application submission through a Ad Hoc distribution (English)
  3) Send the application to the App Store
  4) Create and install an enterprise version of the In-House

References in the @ BoltClock ♦ response from SOEN and in the Ask Different answer

With Jailbreaking

With Jailbreaking it will already be possible through third-party applications. For the case, the most popular is the JailCoder :

  

JailCoder is an easy-to-use tool that patches Xcode and your projects in order to let you install your apps directly on your device.   It includes a step-by-step guided process to patching operations.

What translated:

  

JailCoder is an easy-to-use tool that applies patches to Xcode and its projects in order to let you install your applications directly on your device.   It includes a process for patching operations with step-by-step instructions.