When you acquire a higher level, you keep this new level for one calendar month. If you acquire more clients during the current month, next month your level will switch to a higher one. So, if you have a required number of active clients, you get to the next level at the start of the following calendar month.
You can check your current level on this page in your personal cabinet:
Wanna get more clients? Don't forget to share with them your partner link! Here is how you can generate it right in the cabinet: Partner Link