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.
Sorry. I do not subscribe to the "once saved always saved" get out of jail free card.
It's not in the book.