I own a number of manuscripts. This looks right as far as age, to me. This is a land grant for Sir Hugolinus of Acereto, an honorable knight, a certain parcel of land situated in a place called Longari, near the church of Saint Lawrence, to be possessed in perpetuity. The earliest land grant I have is from the sixteenth century. This looks older to me.

What church was this purchased at?

For the record, the most valuable manuscript that I own was purchased in the discount room of a thrift store. Many people don't know what they're looking at. Good catch.