Disposal of Omamori and New Omamori?

Hi, I will be visiting Tokyo in a week's time.

I had previously gotten an Omamori at Meiji Jingu about 3 years back.

By culture and custom, do I have to return it to the shrine?
Is it okay to just keep it as a souvenir after it has 'lost its power' after a year?

And if I were to get a new Omamori, is it okay to have more than one for myself?
Is it appropriate and okay to be a gift for friends?

Thank you.

Although technically you are supposed to return/destroy them after a year, I never do. You can keep them if you want. And you can absolutely have more than one. There are a lot of different omamori for different things.

Yes, new ones are a nice gift for friends.

If you go to the Meiji Shrine, you can return the old charm to Koshinpu-nosho�iŒÃ�_•„”[�Š�j.
http://www.hitoritabi-ryokouki.com/2014/meijijinguu3.html

I didn't even know they had to be destroyed/returned, I have always kept all of them as souvenirs ^^;