Launch your downloader software, the Service Pack 1 and the 777-300ER expansion for the Base 777-200LR/F are now ready.
The SP1 is “just” a 110 Mb ZIP file that you can get directly from their website. And the longer -300ER variant is for sale at USD 29.99 (about EUR 22.15 /GBP 17.50 ). Note that PMDG requires you to launch PMDG Operations Center software before you apply SP1, to save your livery entries. When you’re done with SP1 setup, launch again PMDG OC so it can restores your liveries and download the updated repaints.
For more information about PMDG, you may read other users questions and comments on Facebook for example.