scook
With the one-time payment method, the software is yours just like all previous upgrades. After your membership ends at the end of a year, you may elects to sign up for another year, go monthly or allow the membership to lapse. There is no continuing obligation to pay Cakewalk anything to use the product you are about to purchase.

If you don't sign up for another year and you need or want updates what happens then?

Also the learning curve to really maximize what you can do what is the best method to learn what you need to learn?
 

BMOG
Only thing I found at that site for $125 http://audiodeluxe.com/products/cakewalk-sonar-professional-academic
http://audiodeluxe.com/products/cakewalk-sonar-platinum-upgrade-sonar-x3-producer

You will not see the final price for the X3-to-Platinum upgrade until after the product is added to your cart. The

BMOG
If you don't sign up for another year and you need or want updates what happens then?

When you decide you need or want updates you will need to either purchase another year or go on the monthly payment plan. Just like you are considering now. The only difference between upgrading from X3 to Platinum and next years event, whether you choose to call it an upgrade or membership renewal, is the product will (presumably) still be called SONAR Platinum.

scook

BMOG
Only thing I found at that site for $125 http://audiodeluxe.com/products/cakewalk-sonar-professional-academic
http://audiodeluxe.com/products/cakewalk-sonar-platinum-upgrade-sonar-x3-producer

You will not see the final price for the X3-to-Platinum upgrade until after the product is added to your cart.

YOU ARE CORRECT WOW!!!

BMOG
Also the learning curve to really maximize what you can do what is the best method to learn what you need to learn?

Check out the SONAR 2015 videos http://www.cakewalk.com/CakeTV/SONAR-University/Get-Started. Read the new features section of the doc http://www.cakewalk.com/Documentation?product=SONAR&language=3&help=NewFeatures.01.html

In X3e I had to get with Melodyne to get it working properly there was a problem with the activation code they gave me they had to give me a new one.  Is Melodyne transferred to Platinum?  Also once Platinum is installed and working can I uninstall all other versions of Sonar or is it better to keep them for just in case purposes?

Only one license for Melodyne is issued with SONAR. You received yours with X3. Melodyne will show as part of Platinum but it is the same license. Do not bother with installing Melodyne again. Platinum will pick up the previous install although it will show as not installed in the Command Center. 
 
You can also skip Rapture and Dpro.
 
If you want to delete old versions of SONAR do it before installing Platinum but if you have the space, it is best to leave them installed. If you manually delete the tutorials in "Cakewalk Content" for each version,  SONAR uses about 200MB of disk space per version. The rest is shared between all the versions installed. Leaving the tutorials on the disk will consume a couple of GB more. Also each version from 8.5 through X3 contain plug-ins not included in newer versions.

scook
Only one license for Melodyne is issued with SONAR. You received yours with X3. Melodyne will show as part of Platinum but it is the same license. Do not bother with installing Melodyne again. Platinum will pick up the previous install although it will show as not installed in the Command Center. 
 
You can also skip Rapture and Dpro.
 
If you want to delete old versions of SONAR do it before installing Platinum but if you have the space, it is best to leave them installed. If you manually delete the tutorials in "Cakewalk Content" for each version,  SONAR uses about 200MB of disk space per version. The rest is shared between all the versions installed. Leaving the tutorials on the disk will consume a couple of GB more. Also each version from 8.5 through X3 contain plug-ins not included in newer versions.

Great point about the plugins from previous versions, so i am assuming Platinum has a Melodyne replacement?

Cakewalk issues one Melodyne Essential license per SONAR license. You received yours with X3 Producer. This is one reason upgrades from versions of SONAR which did not include Melodyne Essential and new users pay more.
 
Melodyne will be shown in the Command Center but there is no reason to install it if you leave your old installation intact. Especially since the original install was challenging.