It appears that when John referred to keeping the commandments in Revelation, this is probably how he defined what they were. Consider the following passages from 1 John.

1 John 5:3
"For this is the love of God, that we keep His commandments; and His commandments are not burdensome."

And what are God's commandments and why are they not burdensome? Earlier in the epistle he provides the answer:

In this passage, John quotes Jesus' command to him and the rest of His disciples (and all who would be His followers) in his own Gospel of Christ:

An interesting point to note is that often when John referred to the Ten Commandments or the Law of Moses, he used the Greek word nómos, which means law (particularly the Mosaic Law). But when he wrote about the teachings and commandments of Jesus, he usually used the Greek word entolé. In his writings, John appears to make distinction between nómos (the old law) and entolé (the new law). Unfortunately, this is not always seen as clearly in an English translation of the Bible. Nonetheless, it appears that the commandments John refers to in the passages above are most likely not the Ten Commandments, as many Sabbatarian Christians claim, but the teachings and commandments of Jesus Christ. There is no evidence from the Greek text that John's use of the word entolé referred exclusively or even primarily to the Ten Commandments, and this is also often true of uses of this word by other New Testament writers. In light of the definition of commandment-keeping found in 1 John 3:23, and assuming John the Revelator is the same John who authored the Gospel of John and 1-3 John, passages in Revelation that speak of it can be better understood.

Revelation 12:17
"And the dragon was enraged with the woman, and went off to make war with the rest of her offspring, who keep the commandments of God and hold to the testimony of Jesus." 

Revelation 14:12
"Here is the perseverance of the saints who keep the commandments of God and their faith in Jesus."

Revelation 22:14 (King James Version)
"Blessed are they that do his commandments, that they may have right to the tree of life, and may enter in through the gates into the city."

Revelation 22:14 (New King James Version)
"Blessed are those who do His commandments, that they may have the right to the tree of life, and may enter through the gates into the city."

This last text is often used by many Sabbatarian Christians to prove that the Ten Commandments, especially the fourth commandment dealing with the Sabbath, will be kept be those who will be saved. But all the oldest and best Greek manuscripts for this Scriptural passage read "Blessed are they that wash their robes ...", so it seems that this verse gives no support whatsoever for commandment-keeping. Consider other Bible translations of this verse:

Revelation 22:14
"Blessed are those who wash their robes, that they may have the right to the tree of life, and may enter by the gates into the city."

Revelation 22:14 (New American Bible)
"Happy are they who wash their robes so as to have free access to the tree of life and enter the city through its gates!"

Revelation 22:14 (Revised Standard Version)
"Blessed are those who wash their robes, that they may have the right to the tree of life and that they may enter the city by the gates."

Revelation 22:14 (New Revised Standard Version)
"Blessed are those who wash their robes, so that they will have the right to the tree of life and may enter the city by the gates."

Revelation 22:14 (Good News Bible)
"Happy are they who wash their robes clean and so have the right to eat the fruit from the tree of life and to go through the gates into the city."

Revelation 22:14 (New International Version)
"Blessed are those who wash their robes, that they may have the right to the tree of life and may go through the gates into the city."

Revelation 22:14 (Darby Version)
"Blessed are they that wash their robes, that they may have right to the tree of life, and that they should go in by the gates into the city."

This is one of the most beautiful passages in Scripture. One full of comfort and hope. John here provides assurance of salvation to those who believe on Jesus Christ, to those who keep their eyes fixed on Him and allow Him to work in their lives. John emphasizes that such believers can know right now that they have eternal life. Not that they may have eternal life, but that they have eternal life.

1 John 5:6-13