AFAIK, lic is the file type for AppMon license starting with 7.0. Before version 7.0, licenses are of file type .key.
I've been there once, in my case is the license team generate the license wrongly. Maybe you can double confirm with the person/team from Dynatrace who generate the license for you?
We switched the AppMon Free Trial to AppMon 7 mid of April. Since that time we also send out the new 7.0 license files which have a .lic extension. Please simply install AppMon 7 which you can find on the Free Trial DOwnload Page: https://community.dynatrace.com/community/display/...
If for whatever reason you need a 6.5 license key please respond to the free trial emails you have received throughout the trial period.