@tamietam Thanks for reaching out. Where are you trying to sign up for a free trial? Which channel are you trying to sign up within?
Have you logged into your Roku account at my.roku.com and updated your payment method again? We'd recommend verifying the account your device is linked to in Settings>System>About, then log into the account and update your payment method. Once you've done this, restart your device, then try subscribing again.
@tamietam Which streaming channel are you trying to sign up for a free trial for? Is this inside The Roku Channel? Do you see an error message on screen or what is occurring when you try to subscribe? With more information, we can continue assisting you from there.