The answer is 'yes' and 'it depends'. You can have 2 systems authorized at one time. You can download and install all products in full except Superior Drummer products (S2 and SDXs). Those require discs.
How to:
Log into your Toontrack account and download the full product installers. Next, download any updates from the Updates section for each product. Install and authorize using the online authorization process or the offline process.