And that, knowing the time, that now [it is] high time to awake out of sleep: for now [is] our salvation nearer than when we believed.
Note 1 at Ro 13:11: Paul had commanded submission to government, and he used two reasons for compliance (see note 8 at Ro 13:5). The most important reason was not just to avoid being caught and punished by the government but to have a good conscience toward God. He was continuing that thought in this verse.
He was saying that the time left before the Lord's return is growing short and that we must therefore be even more sensitive to God. This is the same reasoning that the Lord Jesus used in the parable of the ten virgins and the parable of the stewards and their talents (Mt 25).
The message of these four verses (Ro 13:11-14) can be summed up in the words of Jesus from Lu 21:34. The issue of the Lord's imminent return adds even more importance to us walking in love.