Read from the Lord's Prayer book every day in the morning until you start reading it without book. This is one of the effective ways to memorize the Lord's Prayer and this can also help you remember the prayer in the longer run.
If you cannot read the prayer in the mornings on a regular basis for some reasons, start reading the prayer at meal times, two or three times a day. This is an even better practice that can help you remember the prayer in the longer run.
Start volunteering yourself at your local church to read the Lord's Prayer whenever an occasion arises, and this can help you memorize the prayer. This can also boost your confidence and this should ultimately make you better understand the religious environment and easily memorize and remember things like Lord's Prayer.
Learn the prayer properly from you local church leader. This is a good way of learning and remembering the Lord's Prayer especially when you are not very effective with your reading skills. Taking lessons and then offering to recite the prayer in front of the leader will help you memorize and remember the prayer.
Continue reading the Lord's Prayer and other religious material, even if you do not have to make their practical use. For example, you are not into church gathering and do not appear to be a religious man but do know all prayers, including the Lord's Prayer.
The better way to learn and remember the Lord's Prayer is to make a regular use of it. For example, you should take the matter into your own hands at the family gatherings, even at the regular meal routine and this should help you memorize and remember the Lord's Prayer.
Talk to your local church prayers' leader if you have any particular issue to memorize and remember the prayer. The church is often able to help you out in the matter and might be able to offer some tips to seek a solution that problem. Just do not give up and continue your efforts, and they should repay you back sooner or later.