In WP User Frontend plugin you can enable two types of payment from Users for post submission.
- Pay per post
If you want to force your user to buy a Subscription pack for post submission you need to
Go to wp-admin→User Frontend→Settings→Payment and enable both Charge for posting and Force pack purchase
Then go to Subscription menu and add a new subscription pack. For reference, we have already created a subscription pack. If you are facing any difficulty you can visit here to know more about how to create a subscription pack.
Create a Form from Post Forms menu. Here we created a Sample Form for reference. You can create any type of form you like or if you need guidance you can see this documentation on how to create a form.
Now paste the Shortcode of the Sample Form to Add a new page and hit Preview.
Front end view of force subscription option when a user tries to submit a post.
If the user clicks on the purchase a pack they will be redirected to the available subscription packs that the Admin offers.