This is what they replied me. What do u think?
You are able to use the function pmpro_hasMembershipLevel or pmpro_getMembershipLevelForUser.
When you need the code of a level, do you need to get the level object?
A good place to start is to search the functions.php file for specifics – https://github.com/strangerstudios/paid-memberships-pro/blob/dev/includes/functions.php
Please let me know what information you specifically need for the level code