Where is pay by year AND pay by month on one level option

I only want to offer three membership levels. That’s it! But I want to not only allow monthly payments but I want to be able to collect payment if they want to pay for the entire year at once. I don’t see how to do that and the option isn’t available, just like the checks button isn’t available, although I have all the information in the back. Is there a current gist that makes this possible? Is there a current gist that makes adding the pay by year option available WITHOUT creating another level as I have no desire to do that and that will only cause confusion to my potential members?

https://wordpress.org/plugins/paid-memberships-pro/