The situation in which a trademark cannot be declared invalid after five years of registration may vary depending on the legal provisions of the country and region. In some countries, it becomes more difficult to invalidate a trademark after five years of registration, but this does not mean that action is completely impossible. The following are some common practices:

1. Brand establishment and maintenance: After trademark registration, the holder should actively establish and maintain the visibility and market position of its brand. Strengthen the use and protection of trademarks through advertising, product promotion, brand building and other methods to increase the effectiveness of trademark rights.

2. Monitor and take legal action: Monitor the market regularly for potential infringements. If you find that someone else is using a trademark that is similar or identical to a registered trademark, which may cause confusion or misleading, you can take legal action, such as issuing a warning letter, filing an infringement lawsuit, etc.

3. Trademark renewal: Trademark registration usually has a certain validity period, usually from a few years to decades. Ensure timely renewal of trademark registration to maintain trademark validity and rights.

4. Seek professional legal advice: If you believe that your trademark rights have been infringed but cannot declare the trademark invalid, it is recommended to consult a professional intellectual property lawyer to understand local legal regulations and seek appropriate legal advice.

It should be noted that specific legal provisions and feasible measures will vary from country to country and region to region. When facing infringement of your trademark rights, it is recommended that you consult a local intellectual property lawyer to obtain accurate legal guidance and advice.

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