HT1338 Purchased a used macbook pro with Mountain Lion. My old Mac runs Snow Leopard is backed up to Time machine. How do I register the operating system to me and how do I use Time Machine to move my files to the new used computer?

Question

Purchased a used macbook pro with Mountain Lion. My old Mac runs Snow Leopard is backed up to Time machine. How do I register the operating system to me and how do I use Time Machine to move my files to the new used computer?

Answer 1

If you look at the User Tips tab, you will find a write up on just this subject:
https://discussions.apple.com/docs/DOC-4053
The subject of buying/selling a Mac is quite complicated.  Here is a guide to the steps involved. It is from the Seller's point of view, but easily read the other way too:
SELLING A MAC A
Internet Recovery, and Transferability of OS & iLife Apps
Selling an Old Mac:
• When selling an old Mac, the only OS that is legally transferable is the one that came preinstalled when the Mac was new. Selling a Mac with an upgraded OS isn't doing the new owner any favors. Attempting to do so will only result in headaches since the upgraded OS can't be registered by the new owner. If a clean install becomes necessary, they won't be able to do so and will be forced to install the original OS via Internet Recovery. Best to simply erase the drive and revert back to the original OS prior to selling any Mac.
• Additionally, upgrading the OS on a Mac you intend to sell means that you are leaving personally identifiable information on the Mac since the only way to upgrade the OS involves using your own AppleID to download the upgrade from the App Store. So there will be traces of your info and user account left behind. Again, best to erase the drive and revert to the original OS via Internet Recovery.
Internet Recovery:
• In the event that the OS has been upgraded to a newer version (i.e. Lion to Mountain Lion), Internet Recovery will offer the version of the OS that originally came with the Mac. So while booting to the Recovery Disk will show Mountain Lion as available for reinstall since that is the current version running, Internet Recovery, on the other hand, will only show Lion available since that was the OS shipped with that particular Mac.
• Though the Mac came with a particular version of Mac OS X, it appears that, when Internet Recovery is invoked, the most recent update of that version may be applied. (i.e. if the Mac originally came with 10.7.3, Internet Recovery may install a more recent update like 10.7.5)
iLife Apps:
• When the App Store is launched for the first time it will report that the iLife apps are available for the user to Accept under the Purchases section. The user will be required to enter their AppleID during the Acceptance process. From that point on the iLife apps will be tied to the AppleID used to Accept them. The user will be allowed to download the apps to other Macs they own if they wish using the same AppleID used to Accept them.
• Once Accepted on the new Mac, the iLife apps can not be transferred to any future owner when the Mac is sold. Attempting to use an AppleID after the apps have already been accepted using a different AppleID will result in the App Store reporting "These apps were already assigned to another Apple ID".
• It appears, however, that the iLife Apps do not automatically go to the first owner of the Mac. It's quite possible that the original owner, either by choice or neglect, never Accepted the iLife apps in the App Store. As a result, a future owner of the Mac may be able to successfully Accept the apps and retain them for themselves using their own AppleID. Bottom Line: Whoever Accepts the iLife apps first gets to keep them.
SELLING A MAC B
Follow these instructions step by step to prepare a Mac for sale:
Step One - Back up your data:
A. If you have any Virtual PCs shut them down. They cannot be in their "fast saved" state. They must be shut down from inside Windows.
B. Clone to an external drive using using Carbon Copy Cloner.
1. Open Carbon Copy Cloner.
2. Select the Source volume from the Select a source drop down menu on the left side.
3. Select the Destination volume from the Select a destination drop down menu on the right
side.
4. Click on the Clone button. If you are prompted about creating a clone of the Recovery HD be
sure to opt for that.
Destination means a freshly erased external backup drive. Source means the internal
startup drive. 
Step Two - Prepare the machine for the new buyer:
1. De-authorize the computer in iTunes! De-authorize both iTunes and Audible accounts.
2, Remove any Open Firmware passwords or Firmware passwords.
3. Turn the brightness full up and volume nearly so.
4. Turn off File Vault, if enabled.
5. Disable iCloud, if enabled: See.What to do with iCloud before selling your computer
Step Three - Install a fresh OS:
A. Snow Leopard and earlier versions of OS X
1. Insert the original OS X install CD/DVD that came with your computer.
2. Restart the computer while holding down the C key to boot from the CD/DVD.
3. Select Disk Utility from the Utilities menu; repartition and reformat the internal hard drive.
Optionally, click on the Security button and set the Zero Data option to one-pass.
4. Install OS X.
5. Upon completion DO NOT restart the computer.
6. Shutdown the computer.
B. Lion and Mountain Lion (if pre-installed on the computer at purchase*)
Note: You will need an active Internet connection. I suggest using Ethernet if possible because
it is three times faster than wireless.
1. Restart the computer while holding down the COMMAND and R keys until the Mac OS X
Utilities window appears.
2. Select Disk Utility from the Mac OS X Utilities window and click on the Continue button. 
3. After DU loads select your startup volume (usually Macintosh HD) from the left side list. Click
on the Erase tab in the DU main window.
4. Set the format type to Mac OS Extended (Journaled.) Optionally, click on the Security button
and set the Zero Data option to one-pass.
5. Click on the Erase button and wait until the process has completed.
6. Quit DU and return to the Mac OS X Utilities window.
7. Select Reinstall Lion/Mountain Lion and click on the Install button.
8. Upon completion shutdown the computer.
*If your computer came with Lion or Mountain Lion pre-installed then you are entitled to transfer your license once. If you purchased Lion or Mountain Lion from the App Store then you cannot transfer your license to another party. In the case of the latter you should install the original version of OS X that came with your computer. You need to repartition the hard drive as well as reformat it; this will assure that the Recovery HD partition is removed. See Step Three above. You may verify these requirements by reviewing your OS X Software License.