Not even close to the first.
If anything, Microsoft was late to the game, introducing their first effective license validation system in 2002. People have been finding ways to protect software, video games, and content since the 80's.
The term DRM was actually introduced when MP3's became popular around 1999. The early MP3 players included a feature called "digital rights management" that would actually check the license of the music played back on the player. It would also prevent the user from copying music back off of the player. Needless to say, this was a dirty word among MP3 player early adopters, and we actively avoided these devices.
In the software world, people have been using various forms of access control since the 80's: key codes, hardware locks, even an early version of the "phone home" system that Windows uses now.
Atari and Nintendo both implemented copy protection on their ROM carts. The carts actually had a small chip inside that prevented people from copying the ROM's, as well as preventing people from running homebrew software on the consoles.
Floppy diskettes for the Commodore, Apple, and IBM computers all had various forms of copy protection. (Software that let you bypass the copy protection was, predictably enough, the most pirated software of the day.) Some of it worked, but most of it was a real mess. The problem there was that the software was often tightly coupled to the type of disk drive used to load it; even legit copies of software would often not load on newer drives from the same manufacturer. Also, the circumvention technology kept up with the new methods of protection, so games didn't stay protected for long at all.
With one software system I installed, I actually had to call an operator, read them a code, and get a response. Other programs required a registration code that you would get from the software's creator. The code was usually cryptographically generated based on your information and forever tied to your name.
Other software used to use devices known as "dongles" plugged in to the serial port or the printer port. The dongle had an encryption key burned in to a small ROM chip, and the software would query the dongle to make sure it was there before running. This is still a common practice, actually, and it's where the term "dongle" came from. If someone calls a USB thumb drive or a Bluetooth adapter a "dongle", they're misusing the term. A dongle is a software validation device, not an adapter or a storage device.
People's least favorite copy protection scheme was the "manual" method. The software would tell you to turn to page xxx of your manual and type word x on line y... it was a pretty major annoyance to play games that required this manual check-in system, and I tended to avoid buying those games (or playing them after I bought them.)
And we can't forget analog copy protection methods: Macrovision was developed in the early 80's, and it made its debut in 1984, annoying videotape viewers ever since.