Xbox live gold games permanently free?

I noticed that xbox live Gold offers different games every month for free. My question would be whether I can still play the game for free after a certain period of time or whether I then have to pay for it.

Once you secure the games, you'll have them forever and you won't have to pay for the games again

I think you are confusing something. There's Xbox live Gold and Xbox Game pass (there's also Xbox ultimate). Gold is for playing all games online accordingly, although there are 4 free games per month on top of it, but then when the membership ends you have to buy it or extend your membership. With Game pass this is so that you can access over 100 games for free. You have the choice (as with Gold) 1 month, 3 months or 12 months membership to buy (you can of course also extend it). After membership you can no longer play the games for free. You would have to extend the membership or buy the games.

No as long as the membership lasts

Naturally. But you don't have to pay for the games again. (like free weekend on Steam)

You can play the One games as long as you have Gold membership.

XBOX 360 titles even without.

The games, once loaded, are permanently yours. So you don't have to pay anything because they are part of your gold membership.

Not quite right.

If the gold membership ends they still belong to him. So he doesn't have to buy them again.

Otherwise see my answer.

Then sorry for my (half) wrong statement

You don't have to apologize to me. If only then at the questioner.