Your certification or recertification will have varying lengths depending on the course. On your certificate it will show the issue date (date course completed and passed) and the expiry date.  

All copies of certificates and expiry dates can be found on the Dashboard and then selecting Certificates. The latest, valid certificate will show as downloadable. 

To avoid a lapse in your certification(s) always ensure to purchase and complete any recertification courses before your expiry date.