In 2010, SFD began using and registered the mark "CHECKED UP" to sell red and white checkered clown curly wigs. Later in 2010, SFD granted an exclusive, worldwide license to Wig World, Inc. to manufacture and sell wigs under the CHECKED UP mark for 50 years for a license fee of $1,000 per year. During the first year of that license, Wig World, Inc. sent one sample wig to SFD for SFD's records. Wig World, Inc. has not sent any additional wig samples to SFD since then. Wig World, Inc. always paid its annual license fee to SFD.

In 2012, Lisa, an up-and-coming costume designer, purchased an intent-to-use trademark application for "CHECKIN' IT UP" that was filed in 2011 for wigs by a third party who had not used that mark in connection with wigs or any other business activity. Lisa began using the "CHECKIN' IT UP" mark in 2012 in connection with wigs that look just like SFD's, but are three times larger. Lisa finally obtained a trademark registration for "CHECKIN' IT UP" in 2015. SFD recently learned that none of SFD's "CHECKED UP" wigs were sold between 2011 and 2015 and that its wigs are not currently on the market. Wig World, Inc. has provided proof to SFD that thousands of SFD-licensed wigs were sold in the United States between 2016 and 2017. SFD recently learned about Lisa's "CHECKIN' IT UP" wigs and wants to take legal action to stop Lisa from selling her wigs under that name.

1. Can SFD successfully sue Lisa for likelihood of confusion? Why or why not?
2. Is SFD's license to Wig World, Inc. enforceable? Why or why not?
3. If Lisa could establish trademark rights to "CHECKIN' IT UP," when would her rights have taken effect?
4. Does SFD have a basis to challenge Lisa's 2015 registration for "CHECKIN' IT UP"? Why or why not?