You can check your current active Nano licenses in the Nano licenses page.
To open the Nano licenses page, open the user menu by clicking on your username at the top right corner of the Nano webapp, and click on the Nano licenses menupoint.
The Nano webapp will show you your active license keys formatted into a table. Each row consists of your Nano license key, how many Nano clients you can operate simultaneously with it, and the date when it expires.
Licenses can be bought for you own account directly or as a bundle of tokens for giving them to any account freely.
Directly bought licenses may be set up for recurring purchase for convenience.
When buying a bundle of license tokens keep in mind that the tokens will also have their expiration time that starts at the purchase.