elaborating a bit from perlobj#VERSION($need) :)

UNIVERSAL::VERSION() is like ->can() a "universal"¹ method and ...

This method is called automatically by the "VERSION" form of "use".

     use A 1.2 qw(some imported subs);
     # implies:
     A->VERSION(1.2);
[download]

¹) All classes automatically inherit from the UNIVERSAL class, which is built-in to the Perl core.