Every week you get a 4 unlocks, now you have 2, because you used 2 unlocks, next week you will have 3 or 4 available unlocks (not really sure). But if you run out of unlocks you can mail the developers and receive an extra unlock - https://www.lfs.net/mailus
When I unlock LFS and later close the program. Then i sign out from windows. When I sign in again and open LFS, I have to unlock it again using one of the three unlocks you get once a week. Is it menat to do so or is something wrong? How does it work?
The unlock writes somewhere the license data (plus some identification of PC data which must match) (disk or windows register or who knows where), so next time you run the LFS, it should be unlocked.
Maybe it fails to write these, or you have some OS setup which makes it look as different PC every time you login into windows?
Maybe post full disk path where LFS is installed, it's often recommended to use simple path without space or special characters, like "C:\LFS\" to avoid possible bugs in LFS code handling paths (if this helps, maybe you can report which path is causing error and Scawen could fix it in future version).
Also if you are using some other tools, encrypted file system, some cleaner of registry or some containerization/isolation SW, antivirus, it may help to mention at least names of the SW and OS version, maybe you have something which reverts all changes the LFS does try to write to OS, cancelling the unlock?
Or maybe it's something completely different. (I'm trying to help by suggesting how you can improve the bug report, but I have no good guess why it is happening, so it may be also something different)