After Jesus' visit with the Pharisee, it was natural for Luke to proceed from the account of the forgiven woman to these details about other women who ministered to Jesus and His apostles. It should be noted that Jesus is a wanderer at this time and continued to be one up until His death. He filled His days with "preaching and bringing the glad tidings of the kingdom of God."
In the first century, there were many who were allowed to be possessed by demons in order to demonstrate the power of God over Satan in casting them out. To be possessed by a demon (or a group of demons) and then have it miraculously cast out would cause anyone to be very thankful. There was a Mary in the first century--a native of Magdala--who was at one time possessed by seven demons! But Jesus freed her, and many others also, from the grasp of these demons. It is not surprising that they would consequently be exceedingly grateful and would desire to serve Jesus and learn more as a disciple of His. Another woman mentioned here is Joanna. Some speculate that this woman is the wife of the nobleman in John 4:46ff.
It must be understood that Jesus and His apostles spent their precious time preaching and traveling. They were not physically employed in order to provide for their necessities. However, the three women mentioned (cf. Luke 24:10), along with "many others", provided their necessities. It is likely that they did this out of gratitude for blessings they had received from the Lord. It is still appropriate today for those who are taught the word (whether male or female) to provide for their spiritual teachers (cf. I Cor. 9:11,14; Gal. 6:6).
Although none of us living in the 21st century have been freed of demon possession or heard Jesus preach in the flesh, we, like these women, should be exceedingly grateful for all that the Lord has done for us and should show our gratitude to Him.