I would assume if it was in the lease that tenant can't install their own and has to pay $90 per unit to have them installed, and the lease contained a requirement to remove them in the winter, then it's probably not illegal. I tried to find some legal language and came up completely empty handed. It's a bizarre situation. All I'm finding about odd fees is landlords can't require payment of amenity fees - but can restrict tenants right to access the amenities if the tenant chooses not to pay the fee.