In CiviCRM you can configure a membership to auto-renew, provide the option
or not auto-renew. However, this was not used for the self-signup contribution pages.
Well, from 4.7.19 it is respected and you can easily create membership contribution pages which force auto-renew. (See CRM-20375).
If the membership is set to mandatory auto-renew you will see a message "Membership will renew automatically" where the checkbox used to be. Optional will show a checkbox while no auto-renew will hide it altogether.