Actually you can set this setting Show Blank Tokens to NO, you can refer on my attached screenshot below.

The system will detected if those custom user field date is empty, it will not show anything on the invoice page.

But I would suggest you remove those label text like what you set from the Custom Content on Invoice from your site backend, because system doesn't know which label text is belong to these token, it will only check for the token whether the user to enter anything in the field or not.

For example update to this :

[[USERDETAIL_SPOLECNOST]]

[[USERDETAIL_IC]]

[[USERDETAIL_DIC]]



Členství od: [[SUBSCRIPTION_SUBSCRIPTION_DATE]]

Členství do: [[SUBSCRIPTION_EXPIRATION_DATE]]



Faktura: 2018[[INVOICE_INVOICE_ID]]

DUZP: [[INVOICE_CREATED_DATE]]

Variabilní symbol: 2018[[INVOICE_INVOICE_ID]]

Číslo účtu: 2200631527 / 2010