If you have more than two machines, say like 4, I have Addictive Keys and Drums.  Two of my machines have plenty of drum modules. So let show this scenario that is a reality.
 
 If I have Addictive Keys installed on machines A and B, (they have a lot of drum modules) and wanted to install Addictive Drums on machines C and D, their installer wont let you.  They only way that is possible is to register a new account.  I brought this up to their support and they said they have never come across a scenario.
 
  Interesting since products like Komplete have a 3 machine limit. I've also had more than one license of NI products and didn't have to do that.
  I have 2 licenses of EZ Drummer spread on 4 machines - no problem.
  Multi licenses of IK products under one account.  FXpansion, Finale, Sony, the list goes on.
 
 Basically their process is primitive since it's more tied to your email address.  So I probably won't buy their stuff unless it's Addictive Keys which is really good. 
 
 I do find it odd that Cakewalk decided to partner with them with a product like Addictive Drums. It's says Session Drummer is not good enough and the shop even sells kits for Session Drummer.  With all of the upgrade promos going back to Sonar 2, this one stands out as odd. Z3ta 2 would have been a better promo or one of their other products or even Addictive Keys.  Like I say it's kind of odd and I'm more than satisfied with the X3 upgrade without the 3rd party stuff.
 
 On a side note, I watched some tutorials from CM Magazine that includes a free version of Rapture, I had no clue what a nice synth that is. That's been in my plugin folder for years and didn't know how great this was.   
 

I thought Sonar was a two machine limit. I beg to differ, more than 2 machines is quite unusual.

Seems reasonable that the manufacturer has an upper limit on the number of computers on which you can install their products. XLN has excellent support and they would probably let you exceed that number if you ask them.   

Sonar has kind of an "on good faith" deal. The license initially states you can install and use it on only one machine. Then later it says you may install it on another machine if it's for personal use and you only use one at a time. Conceivably, this could mean three or four computers. Apart from the initial registration I don't think there is even an authorization check when you run.

 Wow! Did any of you actually read the post or maybe my explanation wasn't clear? I wasn't talking about Sonar.
 
 XLN Audio products have a 2 machine limit per email account.   You were missing the point.

kitekrazy
 Wow! Did any of you actually read the post or maybe my explanation wasn't clear? I wasn't talking about Sonar.
 
 XLN Audio products have a 2 machine limit per email account.   You were missing the point.

the quote button is my favorite feature. it shows who your replying to ?
sorry ;-)

I was replying to Alex, who was apparently comparing Sonar's licensing to XLN's. Sorry for any confusion.
Just as a point of curiosity, do you really have four separate machines of which you only use one at a time, and all of them need all the plugs?

Nope I was wondering if you had enough licenses on Sonar to handle XLN's or indeed the other products you quoted... ;)
I figured what was going on was pretty generous compared to third party products.
It appears that maybe what I wrote (17 hours ago) has lost some context to what you wrote originally (edited 4 hours ago). It seems like a completely different post now (memory fails me but I know you've definitely edited it so much so that my reply now seems totally irrelevant ).

OP I think you are missing the point of why Cakewalk would do this. Most Sonar owners are not producer owners I am pretty sure of that. This is offered in Studio and I believe the Home Studio/X3 versions as well. Session drummer or whatever its called is only in producer. Personally I have no interest in buying Sonar producer never will. I don't really like proprietary plug ins that force you into sticking with one DAW should you decide to change. For me Studio is perfect its basically the same software minus some extra plug ins. 

Addictive Drums is only in Producer. And can actually be used freely in other DAWs, because it is a separate complete license, same as Melodyne. That's why they have their own registration.

Also, Alex, I don't think there is a technically enforced limit on Sonar licenses.