Here is free link for getting stack on your PC.
Now after downloading Stack you can use whatapp on pc.
Abother problem which you found is that whatsapp provides account free just for one year so I also have a solution for this.
You can use multiple accounts and fortunately gmail provides you opportunity to make as many accounts you want so I advises you to make multiple account. Use one account for one year then uninstall whatsapp and again download it after some time.
IMPORTATNT: After downloading stacks, all you have to do is to search whatsapp in list from PlayStore and you can now easily use whatapp on PC.
Enjoy!!!
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