Yes.. a better question.
How is grace "a license to sin"?
Grace simply states that it is through God's will and his Son's sacrifice that we enter into heaven. Does that mean that we have a right to go on sinning once we choose Christ? No - but neither does it change the terms of the agreement.
That being said - should I choose to sin are there not consequences? Surely - but those are temporal in nature. The eternal question is always based upon God's terms which were, are and always will be satisfied only by one means. Sorry -longer answer than I intended.