You can allow users on your Directory website to submit their listings for lifetime without any expiry date in two different ways:

Disable all your price packages

Go to Dashboard>> Tevolution>> Monetization>> Price Packages and either delete or disable all the price packages so that they don’t appear on the submit listing form and your users can submit listings without any package. Hence, those submitted listings will not have any expiry date.

How to allow them to submit lifetime listings with price packages?

You might want to charge users but you also want them to submit listings which does not expire, in this case what you can do is you can edit the appropriate price package and under the Package Duration field you can add a long duration, e.g. 100 years.