Which operating system are you using?
Premiere Pro and After Effects are both 64 bit apps and will only be available for download on 64 bit operating systems.
http://forums.adobe.com/message/4505299
http://www.adobe.com/au/products/premiere/faq.html#64bit-support
Why did Adobe make the decision to support only 64-bit operating systems with Adobe Premiere Pro CS5 and After Effects CS5?
With the CS6 update, joining Adobe Premiere Pro, After Effects, and Photoshop as native 64-bit Mac applications are Adobe Encore, Adobe SpeedGrade, and Adobe Illustrator. On Windows, Adobe Premiere Pro, After Effects, SpeedGrade, and Encore are native 64 bit and run only on 64-bit operating systems. Photoshop and Illustrator are native 64-bit Windows applications, but also run on 32-bit operating systems.
By optimizing code for 64-bit operating systems, Adobe is able to deliver the performance gains video professionals require. Creative Suite customers benefit from working on the latest hardware and operating systems, and the majority of video professionals have already transitioned to 64-bit capable systems, such as Mac OS X Snow Leopard and Lion, or 64-bit versions of Windows 7. Because 64-bit operating systems offer superior performance, CS6 and future releases of Adobe Premiere Pro, After Effects, Encore, and SpeedGrade will not support 32-bit operating systems. For an up-to-date list of 64-bit third-party plug-ins for After Effects, visit the After Effects plug-ins page.
