Expiration term of listings

Hello Everyone,

My directory site is pretty much up and running. But here an issue I am having.

All my listings seem to expire after 30/31 days. For my directory I want the basic listing to be indefinite, with no expiration, because they add value to my site. So I would like to change this to indefinite (or at least a significant length of time such as 20 years (?) if there absolutely must be an expiration date.)

Once that problem is solved, I would then like to have paid upgrades be set with finite expirations …. such as one month, one year, 3 years, etc …. But if I could get help on the first issue, I might be able to solve the second by myself.

Thanks in advance,

Smiley.