add function in my Wordpress theme

I am using premiumpress a Wordpress theme with plugins for auctions like eBay, where user can add a listing and bid on listings. My Problem: There is the setting that user just can add listing, if they have a membership. I can select this. If I click on, "yes just user with memberships can add listings, it works. So if user click on ADD Product and he is register but didn't select a membership after he register, he goes to the membership site and have to select a membership. Same function I need for bidding. If user want to bid on an auction, he have to select a membership bevor and be approved from the admin, like if he want to add a listing. Here you can see the listing: [login to view URL] There is a button"BID NOW" if user is not register and he click on it, he get the message that he have to register, this is ok. after he register and want to click again on the button "BID NOW" he should linked to memberships: [login to view URL] After he select a Membership and he payed for it, he can start bidding. If payment didn't work, he can't bid! approvment should me automatic if payment is done. Also after user register, approved should be automatic done. Maybe this is a setting in admin, I don't know. If you read this carefully, start your text "with Lets do this.... " The main function is there by add listings, you just to add this same function also by biddings.