I hope the fix will be published before my "premium trial" ends (in 14 days), so I can decide whether it is worth to pay for a license.
I accidentally became aware of the memory issue when I viewed Activity Monitor about some other unrelated process. RTProtectionDeamon was using 9.3GB (!) of memory. I have lots of memory installed, so it did not cause performance problems (yet). After a restart, memory usage by RTProtectionDeamon started with 30.5MB, steadily increasing. Now, about 20 hours later, it uses 426.5MB.