Resolved About MAC address

We know each computer has an unique MAC. If I buy new computer to replace the old one, does it have the different MAC?

Suppose they are are in the same physical location of my home/office. The old one will go to trash bin.

 

My question is if I throw the old machine away, is the MAC gone?
Intel PRO/1000 MT Adapter is gone along with the desktop. The MAC is useless?

So the manufacturer has to create tremendous MAC address to deal with this issue?

The similar question is a software has a key, the software manufacturer should generate many keys to prevent insufficient usage?

 

Yes.

Yes.

There are 2^48 (281,474,976,710,656) possible IEEE 802 MAC addresses. That's enough for every man, women and child on the planet to have over 40,000 each. In spite of this fact though, "MAC-48" addresses are expected to be exhausted in about 87 years.

As an example, Microsoft uses a 25-character Product Key, such as A12BC-DEF3GH-IJKL4-MNOP5-QR6S7. Since each one of those 25 characters could be an A-Z and 0-9 that means there are 25^36 possibilities, (211,758,236,813,575,000,000,000,000,000,000,000,000,000,000,000,000 possible Keys).