I'm afraid you can't. Here is why:
1. LinkSeam PRO is only an up-sell or upgrade of LinkSeam Lite and LinkSeam Premium which adds PRO features in your LinkSeam app.
2. Since LinkSeam PRO only an up-sell or upgrade you must have LinkSeam Lite or LinkSeam Premium in your account first in order to buy LinkSeam PRO.
3. Even if you buy LinkSeam PRO without buying LinkSeam Lite or LinkSeam Premium you wouldn't be able to use LinkSeam because LinkSeam PRO is depended on the standard product. So, with only LinkSeam PRO you wouldn't be able to login.
Note: In case you bought LinkSeam PRO without buying LinkSeam Lite or LinkSeam Premium consider buying the standard/main product from our sales page here: https://salesp.getlinkseam.com/fe/