Basically what you're talking about is stealing. Let's just call it what it is. It is software piracy. There is no need to call it app sharing, account sharing, or anything else to make it sound OK.
But since you don't seem to grasp the seriousness of the crime that you are talking about committing, let me spell out the penalties for you:
In the United States, the maximum civil penalty is $150,000 per infringement in a lawsuit for a copyright violation. This means that for every single program or work that was illegally copied and/or distributed, the infringer could have to pay $150,000. As you can imagine, a civil suit may cost a violator millions of dollars.
Read more:
Legal Penalties for Software Piracy | eHow.com Legal Penalties for Software Piracy | eHow.com
On the other hand, piracy of software can be seen as a criminal act akin to stealing. In this case, the infringer can be charged with a criminal offense. In the United States, the maximum criminal penalty for copyright infringement is a fine of up to $250,000 and a jail sentence of up to five years. This involves damages that are both monetary and psychological. A prison record can seriously mar the life of any individual.
Read more:
Legal Penalties for Software Piracy | eHow.com Legal Penalties for Software Piracy | eHow.com
By the way, the reason my name is a different color is because I am a developer with published apps in the Windows Phone Store.