Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
we may update or revise these warnings and instructions , so please review them periodically . 

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