It is possible to store the .lic file to the classpath root, however there could be some not obvious issues (i.e. .lic file is loaded by different class loader than used by the PD4ML classes).
As the first step try to save .lic file to the work dir of your application, point to the .lic file location with applyLicense() API call ( https://pd4ml.tech/javadoc/com/pd4ml/PD4ML.html#applyLicense-java.lang.String- ) and enable diagnostics output (pd4ml.setLogLevel(255)).
If the demo banner has gone, remove the applyLicense() call: the work dir is a location, where it tries to find the file by default.
If the banner is still there, inspect the diagnostics output for possible issues