Since version 1.2.4, the WooCommerce Software License plugin got a new unique functionality, a licence group can be assigned to variation/variable products. The process is simple, start by creating some licensing groups:
Within the variations Tab, on each item options, there’s a new setting called Licence Group
Chose from the list the required licence group to be used for this particular variation and save.
The variations does not require a licence group to be assigned, if empty they will not use licensing functionality at all.