This belongs to the same class of errors as it's versus its: a simple mistaking of a contraction for a possessive pronoun.
"Your" is a possessive pronoun used to indicate ownership; e.g. "When your membership expires, renew it online."
"You're" is a contraction of "You are", used in casual writing; e.g. "When you're finished with your meal, please pay at the counter."
To summarize, you're = you are, whereas your = your.
Your versus You’re
Andrea Ong 