Am I obliged to conclude a maintenance contract?

This depends.

Yes, if you are hosting a purchased website on our shared servers. 

Yes, when you are leasing a website from LoginSecure but maintenance is then already included (you are not signing an additional contract with additional costs involved).

No, if you are hosting a purchased website on one of our private servers.

No, if you are hosting a purchased website on third-party servers.

KB Article: https://loginsecure.eu/helpdesk/knowledgebase/view-article/18-am-i-obliged-to-conclude-a-maintenance-contract