Denis-
You could use a “presence” profile to determine when to lock the door when you leave.
For example, when you exit a geofence from AutoLocation, you could trigger an exit event or door locking event. The following article has some details on how you might achieve that as well as links to relevant SmartThings posts:
The tasker-examples tag in the support site has some articles with interesting use cases of SharpTools and Tasker:
https://help.sharptools.io/portal/kb/tags/tasker-examples
And the following post from the SharpTools community might also be interesting to you: