As it became known last week, subscribers to the Adobe Creative Cloud have recently only access to the last two annual versions of the CC programs via the installer -- a new installation of older versions is only possible via detours. The reason for this radical step could and still can only be speculated, because it seems that Adobe is not allowed to comment on the topic. In the meantime, the manufacturer has indirectly confirmed to Apple insiders and Gizmodo that the procedure is based on a legal dispute ("We cannot comment on claims of third-party infringement, as it concerns ongoing litigation.").
Since then, there have been growing indications of a possible counterparty, as a longer document circulates on the Internet which appears to be a current lawsuit filed by Dolby against Adobe in a Californian court. The accusations are based on copyright infringement and breach of contract; the AC3 audio encoding, which from Dolby&s point of view was insufficiently licensed in the years 2003-2017, is the main issue here. It would fit in time that a CC.2017 is now the oldest, still offered version.
As reported, Adobe had written to some subscription customers who still commercially use an old CC version (now no longer authorized by Adobe) and pointed out to them that they might infringe the rights of third parties if they continued to use it. Obviously, there is nothing more specific to be said at this point. The extent to which users of the old Adobe Creative Suite 6 could also be affected by this is still unclear; in contrast to the current subscription model, a one-time license with unlimited duration was purchased here.