Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
( c ) our `` monthly '' subscription is paid in monthly installments . 

```
. OPTIONS: ['Contract by using' 'Choice of law' 'Content removal' 'Jurisdiction'
 'None' 'Unilateral change' 'Arbitration' 'Limitation of liability'
 'Unilateral termination'].