A lot of people are selling this Crunchyroll Lifetime Premium Upgrade Method and doing it as a service. I was going to make my own service but instead, I think I will just post for free. It is working as of now and is the easiest thing to do.
1) Get some cracked VRV accounts. They are often dropped for free or you can buy some.
2) You will need at least 10 VRV Premium Accounts.
3) In the top right press the profile picture then from the dropdown press link Crunchyroll account
4) If the account is already linked you can't unlink it so you need to find one that isn't linked. I normally find one in 10 accounts that I got (private)
5) When you find one that is not linked just link your Crunchyroll account and your account will now be premium Enjoy ;)
Note: The owner of the account can't unlink your Crunchyroll without contacting support. You can change the VRV account's e-mail + password if you want.