Hi Raiden,
1 If the different application you mean is a different site different domain, no you can not use on it.
domain license only work for 1 domain name. on different application, they should use different domain name right? So you can not use the domain license on all of them.
2 for the sub folder, yes you can use on it if this folder is not other application and under the same domain name.
Regards,
Ken