Since you're going to buy the house at the end of the year, what is the issue with not having a copy of the lease? Are you concerned that the owner won't honor the lease?
Even if it's illegal to not give you a copy the owner could tell you he gave you a copy. You must have lost it. I suggest that you take a more friendly approach when asking for a copy of the lease. If you're concerned that he won't honor the lease, be specific and write down what you remember the lease saying that is important to you and ask him to look it over, add parts he remembers and sign it.
If he has an office, go to the office and wait for a copy. If he works out of his home, perhaps he's lost it, himself.
The reason for needing a copy is what would determine how much effort I spent in getting a copy.
You can talk with a landlord/tenant office or attorney to determine your rights.