As long as you did not view the home with the listing agent you have no obligation to be in contact with them. Depending on the contractual obligation between the seller and tha agent, there may be an obligation on the part of the seller to the listing agent even though the listing has expired.
It depends on what your agency agreement stated between you and the agent that you worked with 7 months ago. There may have been a stipulation that if you buy one of the homes that you saw with him within 6 months or sometimes 1 year, he is due a commission.
If you signed no contract with that buyer agent, then you do not have to contact him. However, the seller would likely cooperate with him/her and pay their fee on your behalf. You may even be able to cut the amount of commission since you have already identified the home and simply need the agent to write the contract, negotiate and coordinate with the lender, title company and inspectors. Possibly a flat fee?
This depends on the agreement he had with te home owners at that time. The best source for accurate information is to contact the home owners and have them refer to their listing agreement. The information should be clearly stated in this document.