How can I prevent my subscribers from viewing and editing their data?

If you have a free Laposta account, you can choose a limited number of options to modify the the text and links in the bottom Marketing block (with the Laposta logo). One of the settings you can change here is whether your subscribers can see the 'Edit your data' link, and thus if they can change their own data.

You can change these settings by clicking the Laposta Marketing block and selecting the Settings tab in the left window.

Next, choose the desired option in the 'Show or hide edit link?' pull-down menu: show or hide.