Good question actually, it appears there is very little information out there in regards to validity duration. Based on what I am reading I am not entirely sure it ever expires. I am sure someone from the training side of the house will jump in with some more concrete info. Have you contact Pearson VUE and inquired?
While there is no expiration on our certifications, we expect that our Customers will maintain their knowledge of RSA Solutions by taking advantage of all the great training being made available to them and to renew their certifications on major new releases.