In the myVIP Loyalty Program, you  have certain number of days to maintain or level up in your myVIP Tier status before it expires.
If you earn enough MVPs to maintain your tier, then the remaining amount of days is how long you have to level up.
If you do not level up, then your period and myVIP Tier Point balance will be reset and you will have a new period in which to either maintain your tier again or level up.
Each myVIP Tier is different, to learn more please visit the homepage and click on Learn More in the header.