They also promise 10 years supply for their part numbers, which can be great and prevent a lot of headaches, specially if you manufacture small batches now and then for the same product.
For example, I had a part number from Micron discontinued, and the substitute from Micron was later discontinued with no suggestion of a completely compatible chip. In the end, there was indeed a compatible alternative from Micron itself (even though the page for the discontinued part pointed to an incompatible one), but I was assured by Alliance that I could order their compatible part for 10 years, no need to scramble and recheck everything every other year.