Ex libris = from the library (literally 'from the books'). A standard form of words on bookplates, accompanied by the name of the owner.
The rest is fairly impenetrable. How confident of you of the letters? What you have is odd!
.' Le nostre' isn't Latin but old French spelling for what translates as ' who/ which is ours',' our' . Nai isn't Latin , fcriuerti may be 'scriperti' some form of a word derived from scribo (I write) like e.g. 'scripta' 'things written'. Scriperti doesn't seem to be one itself. Achora isn't Latin. Achor is but achora isn't a form of that noun. As achor means ' the scab or scale on the back of the head '(!) it seems an unlikely word anyway. Per is Latin for through or by means of, che is not Latin but could be an abbreviation for some word; abbreviations are common in inscriptions and in formal records, where scribes would use them for commonly used words .
It may be that the whole text, apart from 'ex libris' is merely decorative and not meant to mean anything.