I suggest you ask in the respective dedicated forums of each plugin and extension since preventing new additions likely varies in each case. The WooCommerce dedicated forum is here. It’s not clear which membership extension you are using.
The easiest method may be to simply hide the menu links or buttons, but any halfway knowledgeable user can still figure out the correct link and navigate to the proper screen. The only secure way to prevent new additions is to either prevent access through PHP code or remove the user’s capability of adding new items. The plugin devs and expert users you can reach through the dedicated forums are in the best position to advise you of the best approach.