Both Premiere Elements 11 and Premiere Pro (recent or earlier) are standalone products.
This is a question for Adobe Sales, not the Premiere Elements Forum.
Adobe Customer Service may be able to help you at the following link which will bring up Adobe Chat when you click on "I still need help."
I am not sure how this will work since Premiere Pro appears to be under the Cloud system whereas Premiere Elements is not.
In addition to what ATR wrote, just exactly what DO you have, and what do you want to add?
If you want to add Premiere Elements to Photoshop Elements, you need to buy Premiere Elements
If you want to add Premiere PRO to Premiere Elements (or Photoshop Elements) you may either pay monthly rent for PPro CC (Cloud) or you may buy PPro CS6 as a standalone product by going to http://www.adobe.com/products/catalog/cs6._sl_id-contentfilter_sl_catalog_sl_software_sl_c reativesuite6.html?promoid=KFPMZ and going to the second page
PPro CS6 is $799 for the full product... no version of Premiere Elements qualifies for an upgrade price