Problem:
A Toolset Form is used to submit posts, and contains fields for start-date and end-date which should be used to automatically set the published status of the post.
Solution:
Toolset includes a feature to expire posts after a certain interval, but not to "enable" them.
You will first want to enable post expiration on Toolset Forms at Toolset > Settings > Forms.
(See https://toolset.com/documentation/user-guides/automatic-post-expiration/.)
Then on an individual form you can set a default interval such as "posts expire 60 days from now" then that will be applied to all posts submitted with the form.
Once such posts are submitted, if you edit the posts in the backend you will see when the post is due to expire, and you can update it from the post edit screen when you save the post.
The expiry date is stored as a UNIX timestamp in wp_postmeta for the post, with the key "_cred_post_expiration_time".
So you can customise this using the cred_save_data hook (https://toolset.com/documentation/programmer-reference/cred-api/#cred_save_data).
So you have your end-date field in the form. You can add a code snippet triggered by the cred_save_data hook which updates the _cred_post_expiration_time post meta according to what was chosen in the form.
An example of such code is given in the thread.
