I have had a URL for a number of years.  It involved an industry with
an unrelated product to the website. Without giving the out the site
name, just consider the ?site name? is a product.  The name can be
found elsewhere as a generic term.

I put the name up for sale or lease only on my website.  I now have
one company interested.  They wanted a test so, with only email
correspondence and no money involved, I set up a ?doorway? referral
and he supplied the Meta data to insert into the web page.  I uploaded
it and a FREE, and available to anyone, counter with a lot of tracking
items.

After 3 weeks my site is on most of all major engines with the new
Meta.and average in the first 5 positions just on the ?name? when my
site name is a search word.

The season for this product is year round.
 
The ?name? product is a specific item with a selling price of $500 to
$900.  Supplies about $30 each and are consumable.  A few other
products are on their site, and they have dealers.

There are about 20 or so competitors who use the ?name? in their Meta
but, because my site name is the product name, I usually list earlier
on the engines.

Finally the question, how would I handle a lease?

I am assuming the worst case, which is cost per click.  The dealership
was foremost in my thoughts, then there is sell the URL, take my
?doorway? and the data to the many competitors.

But I am retired, do not want to work, do not need any tax liability
from a sale and a small monthly income would be a nice supplement.

If you own the domain name and have full control of it, simply come up
with a monthly figure to lease the domain to him. Sign up for paypal
and tell him to send the first months payment. Then go to your domain
management panel and point the nameservers to whatever hosting company
the buyer is using. Then all of the site work is on him and you are
simply renting use of the domain on a monthly basis. While still
maintaining ownership of domain.