Some parts of x86 were licensed, and AMD needed to pay Intel to use them. Then when AMD built on x86 and made x86-64, Intel had to pay AMD to use that, so they

Some parts of x86 were licensed, and AMD needed to pay Intel to use them. Then when AMD built on x86 and made x86-64, Intel had to pay AMD to use that, so they just made an agreement to license both to each other forever. [0] 0: https://en.wikipedia.org/wiki/X86-64#Licensing https://en.wikipedia.org/wiki/X86-64#Licensing