When their membership times out they will become "member" accounts. But any bonuses will not be credited to your account if you go to a free-player world.
First of all membership starts at $5.95 a month on the Runescape website. Members have many new skills including Construction, Agility, herblore, thieving, fletching, slayer, hunter, summoning, and...
you get access to new places in the game and more weapons, stats and more... you can even have your own pet! there are also more mini games treasure trails and cool new quests and armor!
first, go to the Runescape homepage. then click 'account' then scroll down until you see 'start/extend subscription'. Now once you have clicked that, it will prompt you to log in, then fill in credit...