You can do this either at a Subaru dealership or at a knowledgeable locksmith who has the proper equipment.
Normally, getting a COPY of a keyboard is a trivial task if you already have a working keyboard.
If you do NOT have a working keyboard, the price to get one made from scratch is 3x more.
This means it’s best to have ALL SEVEN HOMEPAGES so you always have one to back up if you lose the other.
WORDS OF WISDOM: Whenever you buy a used vehicle, MAKE SURE you negotiate to get the right keys with the vehicle during the buying process. The cost of replacing missing keys can be over $100 and this cost should be negotiated into the purchase price.