Edit (October 2016): see this post to download Autodesk software easily.
This year, Autodesk appears to have finally got its act together in terms of making software downloads and serial numbers available to Subscription customers quickly after the AutoCAD release. For me at least, the serial numbers and downloads were available as soon as I looked for them, so Autodesk deserves praise for improving matters considerably when compared with the last couple of years.
If you’re a Subscription customer about to download AutoCAD 2013, you may be wondering how you can avoid the awful Akamai Download Manager. If you go to the download page, scroll through the various languages and find the product you’re interested in, you will see a Download Now button. Do not click it, because that will trigger an Akamai infestation. Instead, click on the down arrow to the right of the button. That will give you the option of performing a Browser Download. Click that and away you go.
The download sizes listed on the site are nearly double the real size of the downloaded files. The 32-bit version is actually 0.98 GB, not 1.89 GB. When you run the executable, it will unzip itself to expand to that size, but that’s not the size you need to know about when you’re downloading something.
In my case, the download happened at rather less than half the speed at which the trial came down (taking over 30 minutes for the 32-bit version rather than 13 minutes), but that’s not a valid comparison as I used a different Internet connection and a different browser. The file I downloaded from Subscription was byte-for-byte identical to the equivalent file downloaded as a trial.