How much the certificate costs and lasts?

It costs as much as your ID card costs by the government, and lasts as long as well. They are one and the same. Applying for a new ID card / national ID document in Estonia costs 35€ and the document is valid for 5 years. If you forget your PIN code, you can reset it with your PUK codes, but if you also lose your PUK codes you need to apply for a new ID card. The process for getting a new ID card from the moment you applied for it takes no more than 30 days. You can also have it fast tracked for 250€ and get it in 2 days.

But, like the parent said, you have many other options other than the physical ID-card as well. Most people these days use Mobiil-ID or SmartID, which works on your phone and even smart watch. SmartID is completely free and Mobiil-ID is tied to your phones carrier, so the cost varies, but it's a one-time set-up fee of around 5€. Mobiil-ID certificate also lasts 5 years.