When PLEX was introduced into the game, CCP had some serious and legitimate concerns that this new item would be so volatile in the players mind that it had to have certain boundaries. So they implemented a few restrictions on this one item that made it behave differently from all the other items in-game. The biggest difference between the PLEX and other objects was the fact that you couldn't undock with PLEX in your cargohold. It was in fact bound to the station the pilot initially redeemed the PLEX in, only available to put on the market there (or use or whatever). PLEX was also restricted from courier contracts as they couldn't be couriered to anywhere anyway.
Because EVE Online is a complex game, and the players are habitually out-thinking the developers of EVE by taking the game much farther than the original intention, PLEXes were carefully guarded and monitored. Now, after careful deliberation, CCP is willing to take the Pilot's License EXtensions to the next level. The following is a list of changes made:
• CCP will remove the restriction on undocking from a station with a PLEX in your cargo hold
• CCP will remove the restriction that PLEX cannot be put into courier contracts
• CCP will remove the restriction that items (including PLEX) can only be redeemed into NPC stations
• CCP will remove the restriction that items (including PLEX) can only be reverse-redeemed from NPC stations
• CCP will remove the restriction that ETC can only be converted into PLEX while inside an NPC station.
I personally do not deal with PLEXes any more. Sure, there was a time when ole Gabby needed some serious iskies, but now, the brunt of my income is made through Factional Warfare. Yet, back when I did sell PLEXes (GTCs), I always found it a real bother to be hampered by the limitations placed upon them by CCP.
I am eager to see how these new changes pan out, and hope it is for the best, all around.