Final answer:
Out of the provided options, the machinery intended for use over the next seven years is considered a long-term asset because it is intended for use over an extended period beyond one year.
Step-by-step explanation:
The item that would be considered a long-term asset in the list provided is the machinery the company intends to use over the next seven years. A long-term asset is one that a company plans to hold for more than one year and is used to generate revenue over an extended period. In contrast, investments intended for sale within the next three months are short-term assets, a 10-year note owed by the company is a liability, and the company's common stock is an equity instrument and not an asset to the company itself.