Optiseller uses eBay Auth tokens to access your data. To allow us to do this Optiseller will ask you to link your store at appropriate stages.
When starting a tool or signing up for a plan for the first time, you will see a screen like this
When you click on "Link Your Account" you will be presented with the eBay login to allow Optiseller to access your token.
To link a store without signing up for a plan or tool, you can do this via the manage datasources page:
On the manage datasources page, you can either add the store (if it doesn't exist)
Or link the store if it is already listed
Optiseller never stores any account login data, only the tokens which can be revoked by you at any stage.