Tests on expected storage life conducted in house using climate chambers show a durability of approx. 100 years, both for CD-R and DVD-R. This applies to discs stored under certain conditions, with the original burning quality naturally also playing an important role. In that respect, there are preferred burner/media combinations. The method of storage also plays an important role (upright in a jewel case, at approx. 20 – 25°C and 55% relative atmospheric humidity, protected from light, smoke-free etc.).
Each use of a CD-R/DVD-R will normally shorten its useful life, as minor damage such as scratches, fingerprints, dust etc. is difficult to avoid. Careful handling of media is therefore advisable to prolong the discs’ working life. Given the direct influence that the user has, however, no fixed period can be given here.

We cannot comment on the working life of pressed CDs/DVDs, as we have no test data. With a similar quality of manufacture, however, they should last as long as writeable media.