The mayors of the palace were not about to restore the impermanency of charges and offices ; they reigned only by the protection they granted in this regard to the nobility ; thus high offices continued to be assigned for life, and this practice became more and more firmly established.
But I have some particular observations to make on the fiefs. I cannot doubt that from those times most of them had been made hereditary.
In the treaty of Andeli, Gontram and his nephew Childebert commit themselves to maintaining the liberalities made to the leudes and the churches by the kings before them  ; and the queens, the daughters, and the widows of kings are allowed to dispose by testament and forever of the things they hold from the treasury. 
Marculfus was writing his formulas in the time of the mayors.  We see several of them where the kings make grants both to the person and to the heirs  ; and as the formulas are the images of the everyday acts of life, they prove that near the end of the first dynasty a part of the fiefs was already passing on to heirs. It was far from the case that the notion of an inalienable domain was current at that time : it is a very modern thing, which was then known neither in theory nor in practice.
For that we shall soon see proofs of fact, and if I show a time when there were no longer any benefices for the army nor any funds for its support, we will have to concede that the former benefices had been alienated. That time is the time of Charles Martel, who founded new fiefs which we really must distinguish from the early ones.
When the kings began to give in perpetuity, either because of the corruption that crept into the government, or because of the constitution itself which obliged the kings to be to constantly rewarding, it was natural that they should begin to grant fiefs rather than counties in perpetuity. Giving up a few lands was a small matter ; to renounce high offices was to lose power itself.