If you have the appropriate NFT as a voucher, you can use it in OpenArt Studio.

NFT (non-fungible token) or Non-Replaceable Token
It is a type of digital token that represents a unique asset.
These can be fully digital assets or tokenized versions of real assets.
Since NFTs are not interchangeable, they act as proof of authenticity and ownership in the digital realm.

On the OpenSea website, which is a portal dealing with NFT trading, you can purchase NFT vouchers to be used for services in OpenArt Studio.

How it's working?
There are different NFTs depending on the value of the voucher. One NFT may be used once.
For example, if you have an NFT with the designation GOLD 50 PLN Voucher, you have the right to a 50 PLN discount on my services.

The offer is available here:
https://opensea.io/collection/vouchery-openart-studio

NFT technical specification for consultation:

• the tokens are on the Polygon blockchain
• available on the OpenSea portal
• recommended wallets after storage are MetaMask and TrustWallet