There's nothing in the Addon Manager program that controls what keys are enabled or not in the "Register Serial" dialog. All keys are available, and nobody ever reported this so far.
In fact, the most common error users do when failing an activation, is to insert the letter "O" INSTEAD of a "0" (zero), so if this problem was really due to some kind of problem with the program, we should never seen this, when in fact is the most common cause of activations failures and support request about supposedly "wrong" Serials issued. At the same time, I never seen a problem of someone with a real letter "O" in his Serial, not able to insert it.
Speaking about what is the most convenient process, you shouldn't forget that by choosing the purchase on the Web store, which requires purchasing the product on the Web page, waiting for the email with the Serial Number, insert the Serial Number manually and be sure not making typing errors, is not our "real" purchasing method!
It's a BACKUP alternative method, which has the following advantages: it allows purchasing from a different computer than the one FSX is installed into and it allows a PayPal payment.
But if you are paying with regular credit card and you are purchasing on the PC you are using FSX, it's FAR easier to use the Integrated purchase process from the Addon Manager ( the "Buy" button ), because that one has the following advantages:
1) It doesn't require to open the browser and go on the web page
2) It automatically activates the product as soon as you confirm the payment, without having to insert any Serial Number or any other code manually, so there's no risk losing time mis-typing it.
3) The product will be usable immediately, without having to wait for the confirmation email to arrive so, instead of having to use 3 different programs (Browser to purchase, Email client to read the Serial Number and FSX/Addon Manager to insert it), you do everything within FSX, faster and easier.
This is our premier, suggested and proper purchase method.
We used to have only this one a few years ago when we started, but then we added the Web page because some users wanted to be able to purchase from a different PC (at the workplace, for example) than the one they had Flight sim installed, and many prefer to use PayPal, which is not supported in the Integrated purchase method.
But I believe that most of users simply choose to purchase on the Web page, regardless how more cumbersome and prone to error is compared to the Integrated method, because it's similar to and just as cumbersome as any other Web store out there using the traditional Purchase on the Web page->Wait for Email->Register Serial and type it manually method that everybody use.
