Hello tatianna80,
Welcome to Apple Support Communities!
If we understand your post correctly, you want to know if an activity competition ends in exactly 7 days after you start. We're happy to provide some information to you.
With iOS 12 and watchOS 5, you can invite friends to compete in a seven-day competition. During the competition, you both earn points by filling your Activity rings. You get a point for every percent that you add to your rings each day, and you can earn up to 600 points a day. That’s a max of 4,200 points for the week.
Whoever has the most points at the end of the competition wins. When the competition is complete, you earn an award."
For more information check out this article: Share your Activity and compete with friends with your Apple Watch
Let us know if you have any questions.
Thank you for using Apple Support Communities.
Take care!