“The sky is not the limit, it's just the beginning.” ...

 To keep your license current, the FAA requires a biennial flight review with a Certified Flight Instructor –
CFI every 24 months. 

 An IPC, conducted by a CFII, is a full review of knowledge and procedures needed to safely fly an aircraft
on an instrument flight plan flown under actual or simulated (“under the hood”) instrument meteorological flight conditions.