It might seem surprising that such specific trademark issues were included in the Versailles Treaty, but it was a huge document full of such minutiae. Handing German trademarks, such as Aspirine, over to the Entente powers was considered a part of Germany's war reparations. Taking the trademark away from the Bayer company allowed for cheap mass production of Aspirine which made it the chap drug it is today. Heroin is a different story though...

It is interesting to note that Germany was also no longer allowed to use certain foreign trademarks under the Versailles Treaty. For instance, it forbid Germany from using the name "champaigne" for any sparkling wine produced in Germany. That's why most of it is still called "Sekt" until today.