Already, individual providers offer a verify-once, use-many-times solution; so if you access a website that works with the same age verification provider for a site where you’ve already proven your age, you will usually not need to repeat the process.
In addition, many providers have put in place bilateral arrangements to recognise each other’s age checks; making it quicker to access new sites.
As the age verification market matures further, it is predicted that a multilateral “age-attribute exchange” will be formed, along the lines of the model used by payment networks such as Visa & Mastercard, where hundreds of different suppliers of credit and debit cards can all be accepted by a retailer through a single payment system. The Age Verification sector is developing similar mechanisms for interoperability so this level of verify-once, use-many-times is extended across sites, regardless of which AV provider is used.
So in future, you may be asked to prove your age when you first buy a new kitchen knife with your online supermarket order, and you will then never be asked to do so again by any other site where age-restrictions apply to its sales or content.