If you can change the relationship on License from Lookup to Master-Detail, you may be able to rollup your filter conditions to a Rollup Summary Field on Account, and then use that summary field to do your filtering. This depends on what your filters on License are specifically.
For example, if you want to only show Accounts where there is at least one License with Active__c = TRUE, you can use a Number formula field on License:
IF(Active__c == TRUE,1,0). Then create a Roll-up Summary Field (called "Total Active Licenses" maybe) on Account that shows you
SUM(Active__c) from Licenses. This field now identifies how many Licenses on your Account are Active. Your report will then filter on showing Accounts where
Total Active Licenses > 0.
If there is a reason this relationship cannot be Master-Detail, then this functionality can only be accomplished through an Apex Trigger.