Do you just want to open the workbook and see the dashboard?
If yes then you can install tableau reader which is free though you can only see the viz. You cannot edit it.
Or do you want to open and do some development on that?
If yes then you cannot open the workbook if you've finished 14 days trail license period. You have to buy a license.
You can follow the link for more info regarding licensing and different products.
Tableau public is free which you can install for learning purpose though you cannot save/open packaged workbooks. You've to published your work in your public profile.
Let us know if this help.
To just view the workbook, download Tableau Reader: Tableau Reader
In case you want to edit and work on it, use Tableau Public: Download Now | Tableau Public
Downside of Tableau Public is that you can only save your workbook publicly.
Another choice is to buy the licence or request for a trail extension from Tableau by writing them a mail.
If in urgent need, take another laptop, use another mail ID, download Tableau Desktop and start working for 14 more days.
Hope this helps.
All the best.