If you make a claim of some particular effective life, or if you have information regarding the device having a limited life, you must have a basis for the effective life you claim, or are required to offer, or that end users are led by your marketing and their reasonable understandings to expect.
That could be testing of a new product or of an existing product with a new process or material, or it could be based on market experience for an unchanged existing product.
In some cases it may be possible to make a reliable engineering inference if your product is very similar to another already-marketed product for which effective life data is available.