Can I compress my application with UPX and then protect it with WinLicense?

Please, notice that WinLicense might not be compatible with already compressed/packed applications. Some compressors/packers make their own checksums to know if the file has been modified, in that case the application cannot be protected by WinLicense (or any other compressor/protector)

Another important thing to notice is that from the protection point of view, WinLicense works much better with unprotected (not packed) files, because it has access to the original application code/data in order to perform the protection.

Another alternative is to protect with WinLicense and put a compressor on top.