Where does “usage” come from?

usage (Middle English) comes from Old French usage, from Old French -age, from Old Occitan -atge, from Latin -āticum.

Ancestry of “usage”, step by step

Step	Language	Word	Meaning
1	Old French	usage	usage; use; habit; custom
2	Old French	-age	forms nouns with the sense of 'action or result...
3	Old Occitan	-atge	suffix used to form masculine nouns
4	Latin	-āticum	—